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II 


MOTION    PICTURE 

II  HANDBOOK  II 

II  'I 

A  Guide  for 

MANAGERS  AND   OPERATORS 
of  MOTION  PICTURE  THEATRES 


By  F.   H.   RICHARDS'ON 


THIRD  EDITION 


Published  by 
THE     MOVING     PICTURE     WORLD 

Pullman  Building,   17  Madison  Avenue 
NEW  YORK  CITY 


Copyright,  1910 
by 

WORLD  PHOTOGRAPHIC  PUBLISHING  Co. 

Entered  at  Stationers'  Hall, 
London,  England. 

Copyright  in  the  United  States,   1912; 

Copyright  in  Great  Britain,  1912; 

Copyright     in     Canada,     1912, 

by 

CHALMERS  PUBLISHING  COMPANY, 

New  York. 


Copyright  in  the  United  States,  1916; 

Copyright  in  Great  Britain,  1916; 

Copyright     in    Canada,     1916, 

by 
CHALMERS  PUBLISHING  COMPANY, 

New  York. 
All  Rights  Reserved. 


Index  to  Contents 

PAGE 

Aberration,  Chromatic  94,  98,  124 

Aberration,  Spherical 94,  97,  123 

A.  C.  Action— How  to  Trace  It 16 

A.  C.  and  D.  C,  Difference    Between 13 

A.  C  and  D.  C.,  Relative    Efficiency   of 290,  294 

A.  C.  or  D.  C,  to  Find  Out 667 

A.  C  Wires  Must  Be  in  Same  Conduit 240 

Adjusting  Intermittent   Sprocket 461 

Adjusting  the  Tension  Springs 463 

Airdomes    669 

Airdome  Site,  Selecting. . . . . 672 

Alternating  Current,  Definition    of 22 

Alternating  Current,  How    Generated 8 

American   Standard   Projector,    Instructions    for 566 

Ammeter  and  Voltmeter  for  Operating  Room 235,  248 

Amperage 157 

Amperage,   Economic  Limit  of 292 

Ampere. 

Definition   of 19 

Hour,   Definition   of 19 

Term,  Definition  of 23 

What  the  Term  Means 26 

Anchoring  the  Machine 236 

Aperture   Plate  Tracks   Worn 465 

Aperture,   Standard    Size 476 

Arc. 

Calculating  Its  Candle  Power 293 

Comparison  of  Candle   Power 293 

Comparison    of    Candle    Power    from    Mercury    Arc 

Rectifier  and  Through  Rheostat. 294 

Controller  303 

Lamp,  The 268 

Position  of  Crater  of 295 

Stream 291 

Voltage  31,  301,  323 

Architect's    Plans,  Checking  of 668 

Asbestos  Wire  Lamp  Leads 50,  233,  271,  313 

Back  Focus,  Definition  of 92 

Back  Focus,  How  Found 104 

Back  Focus,  Why    Important 122 

Baird    Projector,    Instructions    for 546 

Batteries,  Renewal  of 649 


790334 


MOTION    PICTURE    HANDBOOK 

PAGE 

Calculations,  Electrical 28 

Candle  Power  of  Arc 293 

Capacity,  Wire,  Table    of 42 

Capacity,  Wire,  Figuring    Voltage    Drop 45 

Carbons. 

Arc  Stream 291 

Calculating  Candle  Power  of  Crater 293 

Care    of 289 

Chemicalizing    288 

Economizers 302 

Fresh  Carbons   in  Lamp,  Effect   of 301 

Hard   and   Soft 287 

Hard    Spots 287 

How  Made 284 

Inspect  When  Buying 287 

Mushroom  Cap  on  Lower 299 

Resistance  They  Offer 288 

Set,  Best  Results 301 

Set  for  A.  C 297 

Setting 290 

Side  Lining 300 

Size  of 285,  287 

Solid  vs.  Cored  Lower 286 

Stubs    287 

Why  D.  C.  Crater  Is  Larger  Than  A.  C 290 

Carpeting    647 

Chair,  Operator's 235,  245 

Chalk   Surface  for   Screens 189 

Cheap    Equipment 667 

Choke    Coil 344 

Choke  Coil,  Preddy  Economizer 363 

Chromatic   Aberration 94,  98,  124 

Chromatic  Aberration  of   Condenser  Beam 124 

Cleaning  Carbon   Clamps,   Importance  of 270 

Cleaning    Film 206 

Cleaning   Lenses 108 

Cleaning  Machine  After  Film  Fire 208 

Closets  for  Operator 231 

Coating  for  Screens 183 

Coefficient,  Temperature 39 

Coloring  Incandescent   Lamps 668 

Commutator,  Care  of 372 

Commutator,  Definition  of 21 

Compensarcs,  A.  C 353 

Compensarc,  A.  C,  Rules  for  Operation 355 

Condenser  Holder   266 

Condenser  Holders,  Freddy,  Elbert 267 

Condenser  Lenses,  Distance  from  Film 131 

Condenser  Lenses,  Selecting    128 

Conductor,   Definition  of 22 

Conductors,  To  Find  Area  of 48 

iv 


FOR    MANAGERS   AND    OPERATORS 

PAGE 

Conductors,  Properties    of 40 

Conduit  for  Wires 212,  240 

Conjugate  Foci,  Definition    of 91 

Conjugate  Foci,  Explanation  of 95 

Connections,  Series  and  Multiple .» 330 

Connecting  to  Two  Sources  of   Supply 252 

Cost  of  Light  from  A.  C.  Through  Transformer  and  D.  C. 

Through  Rheostat 294 

Coulomb,   Definition  of 19 

Crater,  Position  of 295 

Cycle,  Definition  of 22 

Diameter   of   Objective   Lens •„ 110 

Difference  Between  A.  C.  and  D.  C 13 

Dimmer,  Definition  of 22 

Direct  Current,  Definition  of 22 

Direct  Current,  How  Generated 11 

Dissolving  Moving  Picture 606 

Dissolving  Shutter    605 

Dissolving  Stereopticon    603 

Distance    Condenser   to   Film 131 

Door    of    Operating    Room 213 

Double  Sets  of  Fuses 86,  252 

Double  Spot,  One  Reason  for 297 

Double  Throw  Connection  for  Projector 250 

Dynamo,    Principle   of   Operation 11 

Edison,    Model    D,    Instructions    for 579 

Economizer,  Hallberg  A.  C 360 

Edison  Economy  Transformer 356 

Edison  Super-Kinetoscope    477 

Efficiency,   How   Calculated • 23 

Efficiency  of  A.   C.  and   D.   C 290,  294 

Electric  Conductors,   Properties  of 40 

Electric  Meters    655 

Electrical  Terms 18 

Electrical  Terms,  Explanation  of 24 

Electricity,    How    Generated 5 

Electro  Magnetic  Field,  Definition  of 22 

Electro  Motive  Force,  Definition  of 22 

Emergency  Announcement  Slides 239 

Emergency  Light   Circuit,   Fusing 86 

Employes    661 

Emulsion  Deposit  on  Tension  Springs 464 

End  Play  in  Intermittent  Sprocket 462 

Equipment   Operating  Room 231 

Equivalent  Focus,    Definition   of 93 

Equivalent  Focus,  How  Measured 104,  108 

Exit   Lights: 640 

Eye  Strain 153,  175,  472 

I7easter  Non-Rewind  Machine 318 

Figuring   Seating  Capacity 643 

v 


MOTION    PICTURE   HANDBOOK 

Film.  PAGE 

Cement   Formulas 197 

Cleaner,  Mortimer    206 

Cleaner,  Ideal    207 

Cleaning    206 

Containers    596 

Description  of 192 

Inspection    of 201 

Leader  and  Tailpiece 199 

Life  of 208 

Measuring    210 

Mending    195 

Moistening  When  Dry 204 

Notching   Pliers 203 

Perforations    194 

Stretched    204 

Thickness  of 194 

Where  to  Keep 203 

Fire-proofing  Solution 189 

Fire  Shutters  for  Ports 222 

Floor  of  Operating  Room 214 

Floor,  Slope  of  Auditorium 640 

Focus,  In  and  Out,  Cause  of 466 

Foot-pounds,  Definition  of 19 

Formostat,  The 365 

Fort  Wayne  A.  C.  to  D.  C.  and  D.  C.  to  D.  C.  Compensarcs.  382 

Fuses  76 

Cartridge 79 

Copper  83 

Emergency  System 86 

In  Case  of  Trouble 84 

Link 80 

Plug  80 

Projection  Circuit 81 

Table  of  Sizes 82 

Where    Installed 85 

Fusing  for  Motor  Generator 82 

Graphite. 

Cap  on  Lower  Carbon 299 

Definition    of 22 

For  Lamp 268 

Where    Obtained 269 

Generator,    Electric 11 

Glass  in  Ports 230 

Ground,  Establishing  Permanent 259 

Ground,  Testing  Rheostats  for 260 

Grounding  Machine,  Reason  for 262 

Grounds    255 

Grounds,  Definition  of 22 

Hallberg's  D.   C.  to  D.  C.  Economizer 415 

Hallberg's  Twentieth  Century  Motor  Generator 419 

vi 


FOR    MANAGERS   AND    OPERATORS 

PAGE 

Haze  on  Screen,  Reason  for 168 

Heating 632 

Heating  and  Ventilating 624 

Height  of  Screen  Above  Floor 181 

High-Class   Projection,  Importance  of 151 

High-Grade   Lenses 110 

Horse  Power,  Definition  of 20 

Inclosed    Switches 64 

Induction,  Definition  of 23 

Inductor,  Power's   359 

Inductor,  Power's,  Size  and  Weight 360 

Insulation    . . 50 

Definition    of 23 

Rubber  Covered 51 

Testing    52 

Weather-proof   53 

Intermittent  Sprocket,  Used  Too  Long. 233,  462 

Keystone  Effect   154 

Keystone  Effect,  Eliminating 156,  468 

Killowatt-Hour,  Definition  of 20 

Lamp,  The 268 

Angle  of 273 

Insulation    272 

Lubrication    of 268 

Necessary  Adjustments 273 

Lamps,    Compared 270-1-2 

Lamphouse,    The 262 

Arc  Projector 265 

Condenser  Holder 266 

Keeping   Clean 265 

Lighting  Interior 302 

Ventilation    262 

Ventilation,  Best    Method 263 

Ventilation,  Effect  of  Lack  of 263 

Leaders  for  Films 199 

Lens  System,   Matching 113 

Lens  Tables  of  Small  Value 105 

Lenses  91 

Altering  Distance  Between  Factors 101 

Cleaning    108 

Cleaning  the  Objective 109 

Diameter  of    Condensing 128 

Diameter  of  Objective 110,  122 

Dirty,  Loss  of  Light 102 

Explanation  of  Focus 95,  101 

Figuring    Sizes 105 

High  Grade 110 

How  Designed 96 

Improving    Definition 102 

Loss  of  Light  in 159 

vii 


MOTION   PICTURE   HANDBOOK 

Lenses  (Continued).  PAGE 

Measuring 103 

Measuring  E.  F.  Accurately 108 

Selecting   Condenser   Lenses 128 

Spread  of  Light  Ray 102 

Table  for  Matching 141 

License  Law,  Draft  of 621 

License,    Operator's 617 

Life   of   Film 208 

Lighting  the  Auditorium 633 

Limelight    Projection 674 

Limit  of   Amperage 292 

Lining  Cam  and   Sprocket   Shafts 466 

Lining  the  Optical  System 112 

Lining  the  Sprockets 460 

Location  of  Operating  Room  Ports 215 

Loss  Through  Resistance 41,  334 

Lugs,  Wire  Terminal 87,    88 

Magnetic   Field,   Definition  of 22 

Martin  Rotary  Converter 405 

Matching  Up  Lens  System 113 

Measuring  Film    210 

Measuring  Lenses    104 

Measuring  Wires     48 

Mechanism,  The    (See  "Projector") 457 

Mechanism,  The,   General  Instructions 457 

Meter,    Reading 657 

Mill-foot  Standard  of  Resistance 42 

Minusa    Screen 187 

Mirror    Screen 185 

Mirroroid    Screen 187 

Mortimer  Film  Cleaner 206 

Moistening  Dry  Film 204 

Motiograph,   Instructions    for 528 

Motor  Drive. 

Do  Not  Belt  to  Fly  Wheel 277 

Elbert    275 

Home-made    279 

Multiple    Clutch 277 

Preddy ' 276 

Wallstad   Projection   Stand 280 

Spring  Switch 274 

Motor  Driven  Machines 273 

Motor  Generator. 

Ammeter   and    Voltmeter 372 

Bearings  Run  Hot. . .  '. 381 

Care  of  Commutator 372 

Fort   Wayne 382 

General  Instructions 368 

Hallberg's  D.   C    to  D.   C.  Economizer 415 

Hallberg's   Twentieth    Century 419 

viii 


FOR   MANAGERS   AND    OPERATORS 

Motor  Generator  (Continued).  PAGE 

Heating  381 

Locating  Installation 368 

Martin   Rotary   Converter 405 

Oil 371 

Sparking     374 

Wagner  Rotary  Converter 407 

Wotton   Rexolux 395 

Multiple  Arc  System 55 

Musicians    663 

Musicians,   Light   for 634 

Objective  Lens,  Cleaning    108 

Objective  Lens,  Description    of 99 

Objective  Lens,  Test   for    Distortion 100 

Ohm,  Definition  of 20 

Ohm,  Explanation    of 27 

Oil   for   Projector 457 

Operating    Room 210 

Door     213 

Equipment    231 

Film    Storage 596 

Floor    214 

Model  Installations : 244-6-7-8-9 

Observation  Port 219 

Ports    215 

Size  of  Feed  Wires 239 

Supplies    232,  234 

Toilet   Conveniences 232 

Vent   Flue 227 

Ventilation    228 

Wiring     239 

Operator  Remaining  at  Machine 235,  279 

Operator's  License    617 

Operator's  Report   623 

Operator's  Tool   Kit 237 

Optical  Axis,   Definition  of 91 

Optical  System,  Lining  Up  of 112 

Outlining  Screen  with  Black 178 

Overspeeding  151 

Persistence  of  Vision 472 

Polarity 5 

Changer    252 

Definition   of 21 

Explanation    of 24 

Ports. 

For  Operating  Room 215 

Glass    in [  230 

Observation    , 7j9 

Shutters    for ' 222 

ix 


MOTION    PICTURE   HANDBOOK 

PAGE 

Power's  6B,  Instructions   for 491 

Preddy  Economizer 363 

Projection    147 

By  Limelight 674 

No  Excuse  for  Shadows 149 

Overspeeding    151 

Projector,   The 262 

Adjusting  Intermittent    461 

Adjusting  Sprocket    Idlers 466 

Adjusting  Top  Gate  Idler 462 

American  Standard,  Instructions  for 566 

Baird,   Instructions 546 

Edison,  Model  D,  Instructions 579 

Edison   Super-Kinetoscope 477 

Eliminating  Keystone  Effect 469 

Emulsion  Deposit  on  Tension  Springs 464 

End  Play  in  Intermittent  Sprocket 462 

Extra   Framing  Carriage 462 

Handling  Small  Screws 476 

In  and  Out  of  Focus,   Cause 466 

Lining   Magazines    of 467 

Lining  the  Sprockets 460 

Lining  Sprocket  and  Cam  Shafts 466 

Motiograph    528 

Oil  for 457 

Power's   6B 491 

Reels   for  Operating  Room 467 

Revolving   Shutter 469 

Shutter  and  A.  C 473 

Standard  Aperture  Size 476 

Take  Up 592 

Take-Up  Adjustment 459 

Tension,  Adjustment  of 463 

Threading  the  Machine 594 

Upper    Magazine   Tension 468 

Worn  Aperture   Plate   Tracks 465 

Worn    Sprocket   Teeth 462 

Properties  of  Conductors 40 

Properties  of  Resistance  Metals 40 

Radium  Gold  Fibre  Screen 188 

Rectifier. 

Comparative  Results 432 

General    Electric 434 

Installation    431 

Light  in  Operating  Room  Objectionable 432 

Mercury  Arc 428 

Trouble  Chart 433 

Tube,  Operating  Principle 429 

Westinghouse    446 

Reflection,   Regular  and   Diffuse 168 

Refraction,  Definition  of 92 

x 


FOR    MANAGERS   AND    OPERATORS 

PAGE 

Relative  Efficiency  A.  C.  and  D.  C 291,  294 

Report,  Operator's 623 

Resistance  34 

As  Applied  to  Projection  Circuit 322 

Circuits,  of,    Figuring   It 44 

Copper  Wire,  of 43 

Definition   of 21 

Devices    337 

Different   Metals,    of 38 

How    It    Acts 34 

Loss  Through 41,  334 

Materials,    Properties    of 40 

Metals,   Properties   of 40 

Rheostats. 

A.  C.  and  D.  C 333 

Adding  Extra  Resistance 327 

Adjustable,  How  It  Works 324 

Amount  of  Heat  Permissible 329 

Coil,  How  to  Make 327 

Coils  vs.  Grids 329,  330 

Examining  Connections 328 

Extremely  Wasteful 333 

Fan  Blowing  On 328 

Figuring  Connections 335 

Fixed  Resistance  of  Adjustable 325 

Home  Made  of  Iron  Wire 329 

How  to  Reduce  Noise  When  Using  Them  on  A.  C.  333 

Inductive  Effect  of   A.   C 333 

Locate  It  Outside  of  Operating  Room 328 

Location   of 227 

Near  Ceiling  and  Vent  Flue 328 

Resistance  Rises  with   Age 336 

Temporary  Repair 326 

Use  on  A.  C.  Bad  Practice 333 

Use  Grid  Type  on  A.  C 333 

What  Happens  if  Spirals  of  Coils  Touch 337 

What  They   Do 322 

Wire  Coil,  What  They  Are. 337 

Why  Noisy  on  A.   C 333 

Rule  of  Thumb 32 

Screen,    The 166 

Areas     165 

Chalk  Surface 189 

Character   of   Surface 169 

Coatings    183 

Distribution    of    Light 170 

Eye    Strain 175 

Fire-proofing 189 

Flat   Surface 177 

Height   Above   Floor 181 

Illumination,  D.  C.  and  A.  C 291 

xi 


MOTION    PICTURE    HANDBOOK 

Screen  (Continued).  PAGE 

Illumination    Percentages 164 

Interfering  Light 169 

Locating  at  Front  of  House 180 

Metalized    Surface 172 

Minusa  Gold  Fibre 187 

Mirror    173,  185 

Mirroroid    186 

Outlining  the  Picture 178 

Putting  on  the  Cloth 191 

Radium  Gold  Fibre 188 

Reason  for  Haze 168 

Reflection  of  Light 168 

Simpson    Solar 186 

Size  of  Picture 181 

Stippled    Surface 189 

Stretching  Its    Surface 190 

Table  of  Areas 165 

Tinted   Surfaces 178 

Transparent  174 

Where  Vaudeville  Is  Used 181 

White  Wall  or   Sheet 171 

Seating    642 

Seating,   Figuring   Capacity 643 

Seating,  Loge  Seats 643 

Series  and  Multiple  Connections 330 

Setting  the  Carbons 290 

Short   Circuit,   Definition   of 21 

Shunt    Circuit,    Definition    of 21 

Shutter. 

Distance  from  Lens 474 

Inside  and  Outside 475 

Revolving,  Principle  of 469 

Three  and  Two  Wing  and  A.  C 473 

Side  View,   Effect   of 154 

Simplex    Mechanism,    Instructions    for 513 

Simpson    Solar    Screen 186 

Size   of    Picture 181 

Slide    Coatings 615 

Slides, 

Coloring 614 

Emergency    239 

Handling    Them 612 

Making  Them 612 

Stereopticon    609 

Slope  of  Auditorium  Floor 640 

Soldering    Fluid 90 

Spherical   Aberration 94 

Splices,  Wire 89 

Spotlight,   The 598 


FOR    MANAGERS   AND    OPERATORS 

Sprocket.  PAGE 

Adjusting  Intermittent 461 

End  Play  in  Intermittent 462 

Idlers,  Adjusting 466 

Teeth,  Worn 462 

Static  Electricity,   Definition  of 22 

Stereopticon,  The 600 

Coloring    Slides 614 

Dissolving    Shutter 605 

Handling  the  Slides 609 

Making    Slides 612 

Slides  609 

The    Dissolver 603 

Street   Mains,   Definition   of 22 

Supplies  for  Operating  Room 232,  234 

Switchboards     67 

Switchboards,  Exit  and  Emergency 72 

Switchboards,  Stage   73 

Switches    63 

Care  of 66 

Inclosed    64 

Metal  Cabinet  for 67 

Proper  Location  of 64 

Use  of  Various  Types 65 

Synchronism,  Definition  of 24 

Tables. 

Carbon  Sizes 287 

Experiments  with  Arc 301 

Millimeter    Equivalents 289 

Screen  Areas 165 

Screen  Illumination  Percentages 164 

Small  Wire  Diameters 314 

Stereo    Lenses 107 

To   Match  Lenses 141 

Wire   Capacities 42 

Take-Up   Adjustment 459 

Take-Up,   Faults  of   Old  Style 592 

Temperature  Coefficient 39 

Temporary   Show,   Connecting  Up  for 664 

Tension  Spring,  Adjusting 463 

Terminals,    Wire .....87,    88 

Terms,  Electrical,  Definitions 18 

Terms,  Electrical,  Explanation  of 24 

Test  Lamp  for  Grounds 257 

Testing    Insulation 52 

Testing  Objective  Lens  for  Distortion 100 

Testing  Rheostat   for   Ground 260 

Testing  Voltage   666 

Threading    the   Machine 594 

Three-Phase    Current 17 

xiii 


MOTION    PICTURE   HANDBOOK 

PAGE 

Three-Wire  System    56 

Three- Wire  System,    Connecting   Arcs 242 

Toilet  Conveniences  for  Operating  Room 232 

Toledo  Non-Rewind 315 

Tools  in  Order 238 

Tool  Kit  for  Operator 237 

Torque,   Definition  of 23 

Transformer,   The , .  343 

Action    of 345 

Auto 346 

Compensarcs    353 

Construction  of 343 

Definition    of 23 

Edison  Economy 356 

Fusing 351 

Hallberg  A.  C.  Economizer 360 

How  Amperage  Is  Changed 349 

Power's  Inductor 359 

Primary  vs.  Secondary  Terms 344,  349 

The  Formostat 365 

Theory  It  Utilizes 345 

Wiring  of  Compensarc 354 

Two-Phase  Current 18 

Two-Wire  System 

Use  of  Electrical  Terms  in  Calculations 28 

Vent  Flue  for  Operating  Room 227 

Ventilation  and  Heating 624 

Ventilation  for  Operating  Room 228 

Ventilation,    Winter 633 

Volt-Coulomb,  Definition  of 19 

Volt,  Definition  of 20 

Voltage  Drop,  Figuring  It 45 

Voltage,  Explanation  of 25 

Warning,    A 668 

Watt,  Definition  of 20 

Watt,  Explanation  of  Term 27 

Watt-Hour,  Definition  of 20 

Watt  Meter,  Definition  of 23 

Weather-proof  Insulation 53 

Wire. 

Capacity,  Figuring  Voltage  Drop 45 

Capacity,  Table  of 42 

Gauges     49 

Measuring 48 

Splices  89 

Systems   54 

Terminals     '. 87,  88 

Wiring  the  Operating  Room 239 

Worn  Machine  Parts,  Do  not  Use  Them 233 

Worn    Sprocket   Teeth 233,  462 

Wotton  Vertical  Rexolux. 395 

xir 


Acknowledgement  Is    Hereby   Made 

to 
Mr.  B.  M.  SPENCER, 

Attleboro,  Mass., 

For  the  Drawings   for  a  Large 

Number  of  the  Cuts  in 

This  Handbook. 


xv 


Author's  Note 

TO  FIRST  EDITION 


THIS  book  is  dedicated  to  the  motion  picture  operator  as 
a  token  of  appreciation  of  the  important  part  he  plays 
in  the  presentation  of  the  photoplay.    That  it  may  be 
helpful  in  hastening  the  day  of  perfect  motion  picture  pro- 
jection is  the  desire  of  the  writer,  and  he  trusts  that  a  careful 
perusal  of  its  pages  may  stir  the  ambition  and  increase  the 
ability  of  every  reader. 

October,  1910. 


Publishers    Note 

TO  FIRST  EDITION 

THE  remarkable  vogue  of  the  motion  picture   and  the 
rapid  strides  it  has  made  in  public  favor  as  an  enter- 
tainment and  educational  factor  have  had  their  draw- 
backs.    Chief   among   these    has    been   the   impossibility   of 
securing    a    sufficient    number    of    men    with    the    necessary 
knowledge  and  experience  to  fill  important  positions. 

THE  MOVING  PICTURE  WORLD  has,  in  no  small  measure,  con- 
tributed to  the  success  of  the  picture,  and  the  articles  in  this 
book  were  written  to  give  helpful  information  in  regard  to 
the  many  problems  that  may  arise  in  connection  with  the 
duties  of  the  manager  and  operator.  With  a  few  exceptions, 
the  articles  have  already  appeared  in  THE  MOVING  PICTURE 
WORLD,  but  they  have  been  revised  and  amplified  and  are 
herewith  presented  in  compact  form  to  comply  with  popular 
request. 

Mr.  Richardson  has  avoided  technical  terms,  and  his  plain 
language  and  matter-of-fact  style  bespeak  for  this  book  the 
same  degree  of  popularity  which  attaches  to  the  Operators' 
Column  which  he  still  conducts  in  the  pages  of 

THE  MOVING  PICTURE  WORLD. 
October,  1910. 


Author's    Note 

TO  SECOND  EDITION 

LIKE  the  former  edition,  this  book  is  dedicated  to  the 
moving  picture  operator,  upon  whose  skill  in  the  pro- 
jection of  the  magnificent  work  of  our  modern  pro- 
ducers so  very  much  depends.  Since  the  inception  of  the 
Projection  Department  of  THE  MOVING  PICTURE  WORLD  and 
the  publication  of  the  first  book  rapid  strides  have  been 
made  in  the  perfection  of  projection.  The  author  hopes  and 
believes  that  this  work  will  serve  to  even  further  advance  and 
perfect  projection  to  the  end  that  the  photoplay  may  become 
still  more  firmly  fixed  in  the  affections  of  the  amusement- 
loving  public. 

October  30,  1912. 

Publisher's   Note 

TO  SECOND  EDITION 

THE    enormous    increase    in    popularity    of    the    motion 
picture  during  the  'past  few  years  in  all  countries  is 
one  of  the  marvels  of  the  day.     The  moving  picture 
is  now  far  in  advance  of  all  other  forms  of  public  entertain- 
ment among  all  classes  and  draws  a  daily  patronage  that  is 
beyond  belief. 

In  no  other  country,  however,  do  the  pictures  have  quite  as 
good  a  hold  on  the  public  favor  as  in  the  United  States.  This 
is  in  great  measure  due  to  the  enterprise  and  higher  ideals  of 
the  film  manufacturers  in  this  country.  It  is  also  due  in  great 
measure  to  the  care  and  attention  given  to  programs,  theater 
management  and  especially  the  projection  of  the  pictures  by 
the  exhibitors  throughout  the  United  States  and  Canada. 

The  first  edition  of  this  work  was  published  over  two  years 
since  and  has  been  of  immense  value  and  help  to  operators 
throughout  the  country.  This  edition  has  been  greatly  en- 
larged and  will  be  found  much  more  complete  in  every  way. 
It  will  undoubtedly  remain  the  standard  work  in  its  field  for 
many  years  and  is  a  worthy  monument  to  its  author's  ability 
and  painstaking  effort. 

CHALMERS  PUBLISHING  COMPANY. 

November,  1912. 


Author's    Note 

TO  THIRD  EDITION 

AS  in  the  case  of  the  first  and  second  editions,  I  believe 
it  is  but  right  and  proper  that  this,  my  latest  effort, 
should  be  dedicated  to  the  moving  picture  operator, 
upon   whose  shoulders  rest,  in  large   degree,  the   welfare  of 
the  entire  moving  picture  industry.     The  author  has  faith  to 
believe    that    this   book   will    be    favorably    received    by    the 
fraternity  and  trusts   it  will   accomplish  a  large   amount  of 
good  for  all  students  of  projection. 

In  order  to  do  justice  to  the  magnificent  productions  of 
today  it  is  necessary  that  the  moving  picture  operator  have 
a  wide  range  of  knowledge  and  that  he  be  capable  of  apply- 
ing that  knowledge  in  the  best  possible  way.  The  day  of 
guesswork  in  projection  is  past.  The  author  feels  that  while 
this  book  will  be  of  great  aid  to  the  moving  picture  operator, 
it  will  also  indirectly  be  of  equally  great  help  to  the  pro- 
ducers and  all  others  connected  with  the  industry  by  reason 
of  the  fact  that  it  is  the  finished  product  which  is  placed  in 
the  hands  of  the  moving  picture  operator,  who  may  either 
reproduce  it  on  the  screen  as  a  magnificent  spectacle  or  a 
shadowy,  jumping  travesty  on  the  original. 

November,  1915. 


Publisher's   Note 

TO  THIRD  EDITION 

THERE  is  little  to  add  by  the  Publishers  in  introducing 
this   new  edition.     The   first  and  second  editions   of 
this    work    were    most    complete    and    instructive    at 
the  time  of  their  publication.     Each  edition  was  an  improve- 
ment over  the  previous  one,  and  this  book  much  more  than 
either    of    its    predecessors    not    only    reflects    the    wonderful 
progress  and  improvement  in  moving  picture  projection  but 
points  the  way  to  still  greater  advancement. 

The  author  has  spent  all  of  his  time  for  many  years  in  the 
study  of  projection,  and  we  confidently  believe  this  com- 
prehensive work  will  meet  with  the  unqualified  approval  of 
every  reader.  CHALMERS  PUBLISHING  COMPANY. 

December,  1915. 


Go  to  your  work  each  day 
as  though  it  were  your 
first  day  on  a  new  job 
and  you  had  to  make  good. 


Polarity 


IN   order  to  have  a  comprehensive  understanding  of  elec- 
trical action  it  is  essential  that  the  operator  have  a  very 
clear  and  thorough  understanding  as   to  precisely  what 
polarity  means,  and  how  it  acts,  because   the  whole  super- 
structure of  electrical  action  rests  thereon. 

The  electric  circuit  with  which  the  operator  comes  into  con- 
tact consists  of  two  wires — no  more  and  no  less.  There  may 
appear  to  be  more,  as,  for  instance,  in  a  three-wire  system, 
but,  as  a  matter  of  fact,  so  far  as  electrical  action  be  con- 
cerned, every  electric  circuit  is  composed  of  two  wires,  viz.: 
the  positive  and  the  negative,  and  it  is  the  affinity  these  two 
wires  (which  represent  the  poles  of  the  dynamo)  have  for 
each  other  which  constitutes  "polarity."  There  always  has 
been  and  still  is  controversy  between  eminent  theoretical 
electricians  as  to  the  exact  nature  of  the  action  which  takes 
place  as  between  the  positive  and  the  negative  wire.  To  avoid 
all  confusion,  however,  we  will  lay  aside  technical  questions 
and  accept  the  common  statement  that  current  seeks  always 
to  flow  from  the  positive  to  the  negative.  Having  accepted 
this  as  the  fact  it  may  be  further  said  that  the  inclination  of 
the  current  to  escape  from  the  positive  to  the  negative  is 
similar  to  the  efforts  of  steam  to  escape  from  the  boiler  into 
the  open  air.  When  steam  escapes  from  the  boiler  to  the 
open  air  it  loses  its  pressure  in  the  process.  When  electrical 
energy  escapes  from  the  positive  to  the  negative  it  does 
exactly  the  same  thing,  and  that  is  why  it  seeks  to  escape; 
also  that  is  why  it  will  perform  work  in  the  process  of  escap- 
ing. The  pressure  in  the  boiler  will  force  the  steam  to  the 
open  air  through  the  cylinder  of  an  engine,  moving  the  piston 
and  thus  performing  work  in  the  process.  The  electric  cur- 
rent will  perform  work  in  the  motor  or  the  lamp,  since  it  can 
get  from  positive  to  negative  by  so  doing  and  thus  lose  its 
pressure.  This  electrical  affinity  is  termed  "polarity,"  and  its 
strength,  which  may  be  much  or  little,  is  measured  in  volts. 


6  MOTION    PICTURE   HANDBOOK 

And  now  let  me  make  one  point  very  clear.  Electrical 
affinity  or  polarity  only  exists  between  the  positive  wire  and 
the  negative  wire  attached  to  the  same  dynamo  or  battery. 
There  is  absolutely  no  electrical  affinity  between  the  negative 
wire  attached  to  one  generator  and  the  positive  wire  attached 
to  another  generator,  unless  the  generators  themselves  are 
electrically  coupled,  as  in  the  case  of  the  three-wire  system. 
You  could  set  two  generators  running,  side  by  side,  each 
generating  500  volts,  and  touch  the  positive  of  one  generator 
to  the  negative  of  the  other  machine  without  any  effect  what- 
ever, but  the  instant  you  touch  the  positive  of  either  one 
to  the  negative  of  the  same  machine  there  will  be  fireworks. 

And  now  let  us  go  a  little  further:  The  general  idea  is  that 
current  seeks  to  escape  from  the  wires  into  the  ground. 
This  is  not  true  except  in  so  far  as  the  ground  may  offer  a  path 
from  positive  to  negative.  If  you  could  have  a  generator 
and  wire  system  working  at  5000  volts,  or  any  other  voltage, 
thoroughly  and  completely  insulated  (a  condition  never  found 
in  actual  practice),  you  could  stand  with  your  bare  feet  on 
the  wet  ground  and  handle  either  wire  of  the  circuit  without 
any  danger  whatever,  but  the  instant  one  of  the  .wires  develops 
current  carrying  connection  with  the  ground  and  you  stand 
on  the  ground  and  touch  the  other  wire  you  get  a  shock,  by 
reason  of  the  fact  that  the  current,  leaping  through  your  body 
into  the  earth  and  following  the  earth  to  the  location  of  the 
ground  on  the  opposite  side,  makes  escape  into  the  negative. 
If  you  happen  to  be  holding  the  negative  wire,  that  makes 
no  difference,  except  that  instead  of  escaping  into  your  hands 
and  passing  through  your  body  into  the  earth  the  current 
escapes  through  the  ground  at  the  positive  into  the  earth, 
follows  the  earth  to  your  body  and  up  through  your  body 
to  the  negative. 

In  closing  this  topic  let  me  repeat  that  the  term  polarity 
expresses  the  electrical  difference  between  positive  and 
negative. 

How  Electricity  Is  Generated 

MORE  and  more  it  is  becoming  essential  that  the  mov- 
ing picture  operator  have  a  comprehensive  knowledge 
of  electrical  action,  not   only  as  pertains  directly  to 
the  projection  arc  circuit,  but  also  as  relates  to  dynamos  and 
motors.     An  ever  increasing  number  of  moving  picture  thea- 
tres are  installing  either  motor  generator  sets  or  mercury  arc 
rectifiers  for  the  changing  of  alternating  current  into  direct 


FOR  MANAGERS  AND  OPERATORS      7 

current,  or  else  isolated  light  plants  consisting  of  a  dynamo 
driven  by  a  gas,  gasoline,  kerosene  or  steam  engine.  The 
operator  is  usually  the  man  who  is  expected  to  take  charge  of 
and  operate  these  isolated  plants,  and  most  certainly  it  is  a 
part  of  his  duties  to  handle  and  take  care  of  a  motor  gener- 
ator set,  or  other  device  used  for  the  rectifying  of  current. 
Therefore,  I  repeat,  the  up-to-date  competent  moving  picture 
operator  must  have  a  very  comprehensive  knowledge  of  elec- 
trical action. 

This,  the  third  edition  of  my  Handbook,  is,  like  former 
editions,  a  work  for  practical  men.  In  this  book  I  shall,  as  I 
have  in  the  past  editions,  pay  a  great  deal  more  attention  to 
practical  things  than  to  fine-spun  theories  and  strictly  tech- 
nical correctness. 

We  do  not  know  the  precise  nature  of  the  force  we  call 
electricity.  We  do  not  know  what  it  consists  of.  Its  com- 
ponent parts  have  never  been  analyzed.  We  only  know 
that  it  is  a  mighty  force,  which  apparently  has  neither  sub- 
stance nor  weight.  It  is  a  peculiar  state,  or  condition,  in  and 
immediately  surrounding  a  wire  attached  to  a  battery  or 
generator  which  is  not  found  in  any  wire  not  so  attached. 

We  do,  however,  know  how  to  handle  this  mysterious  force, 
and  bend  it  to  our  will.  In  fact,  our  knowledge  of  electrical 
action  has  become  so  complete  that  the  mighty  giant  is  as  a 
child  in  our  hands.  We  have  chained  it  to  the  wheels  of 
progress,  and  it  has  become  a  slave  to  mankind. 

Electricity  may  be  divided  into  three  distinct  classes,  viz. : 
Static  electricity,  magnetism  and  electric  current,  meaning, 
by  the  latter,  current  which  is  generated  by  batteries  or  by 
an  electric  dynamo. 

If  you  take  a  glass  jar,  of  any  convenient  size,  fill  it  two- 
thirds  full  of  water,  and  then  put  in  ordinary  sal  amoniac  in 
proportion  of  a  pound  to  the  gallon  of  water,  and  in  this 
solution  suspend  a  piece  of  ordinary  sheet  copper,  of  con- 
siderable dimensions,  and  near  to  it  but  not  touching  suspend 
a  piece  of  zinc,  also  of  considerable  dimensions,  you  will  have 
the  simplest  form  of  what  is  known  as  an  "electric  battery." 
Now  if  you  join  the  copper  to  the  zinc  by  means  of  a  piece  of 
copper  wire,  current  will  flow  between  the  two,  or,  more  cor- 
rectly speaking,  from  the  copper  to  the  zinc,  the  copper  being 
positive  and  the  zinc  negative.  A  properly  proportioned  bat- 
tery of  this  sort  will  generate  about  one  volt  pressure,  and 
will  put  forth  a  considerable  amperage  while  it  lasts.  It  would 
be  theoretically  possible  to  construct  and  connect  together 


8 


MOTION    PICTURE    HANDBOOK 


a  sufficient  number  of  batteries  of  this  kind  to  operate  a  pro- 
jection arc  lamp,  but,  though  theoretically  possible,  it  would 
nevertheless  be  highly  impractical.  In  practice  the  use  of  the 
battery  is  largely  confined  to  the  ringing  of  bells  and  buzzers, 
the  operation  of  telegraph  instruments  and  similar  light  ser- 
vice where  but  comparatively  little  energy  is  required. 

Electric  current  used  for  ordinary  light  and  power  purposes 
is  generated  by  what  is  known  as  a  dynamo,  or  generator,  the 

two  terms  being  inter- 
changeable when  used  in 
this  connection.  The  dynamo 
depends  for  its  action  upon 
magnetism,  and  the  fact  that : 
When  an  electric  conduct- 
or is  moved  in  an  electric 
field  a  current  of  electricity 
is  generated  therein  which 
will  flow  in  a  direction  at 
right  angles  to  the  line  of 
motion. 

,  .  In  Fig.   1   we  see  this  law 

illustrated,  N  and  S  being  the 

q  north  and  south  poles  of  an 

f  V  ordinary    horseshoe    magnet, 

the  dotted  lines  representing 
magnetic  "lines  of  force," 
which  constantly  flow  between 
the  poles  of  all  electric  mag- 
nets. The  space  occupied  by 
these  lines  of  force  is  termed 
a  "magnetic  field,"  and  with 
a  magnet  of  the  type  shown 
in  Fig.  1  this  field  is,  of  course,  strongest  directly  between  the 
poles. 

A  represents  an  electric  conductor,  say  an  ordinary  copper 
wire,  with  its  ends  joined  by  wire  B,  so  that  a  continuous  cir- 
cuit is  formed.  If  this  wire  be  moved  upward,  in  the  direc- 
tion of  arrow  A,  an  electric  current  will  be  generated  therein, 
which  will  flow  along  the  wire  in  the  direction  of  arrow  C,  or 
at  right  angles  to  the  line  of  motion.  //  the  wires  were  moved 
downward  through  the  magnetic  field  in  the  direction  of  arrow 
X,  instead  of  up,  the  current  in  the  wire  would  flow  in  the  op- 
posite direction,  as  per  dotted  arrow  Y,  it,  of  course,  being  under- 
stood that  the  ends  of  the  wire  passing  through  the  magnetic 
field  must  always  be  joined,  so  that  a  complete  circuit  is  formed. 


Figure  1. 


FOR  MANAGERS  AND  OPERATORS 


No  current  would  flow  if  the  wire  were  merely  a  straight  length, 
with  its  ends  unjoined. 

Now  let  us  take  a  step  in  advance  and  examine  Fig.  2.  Re- 
membering that  if  the  electrical  conductor  in  Fig.  1  be  moved 
upward  the  current  will  flow  to  the  right,  and  if  it  be  moved 

downward  it  will  flow  to  the 
left,  transfer  your  gaze  to 
Fig.  2,  where  you  will  see  a 
loop  of  wire,  X  X,  so  ar- 
ranged that  it  may  be  rota- 
ted on  a  spindle.  One  end 
of  this  loop  connects  to  ring 
A,  and  the  other  end  to 
ring  B,  and  the  ends  are 
joined  by  means  of  brushes 
C  and  D  and  the  wire  E 
(outside  circuit)  attached 
thereto.  Now  if  we  revolve 
this  wire  loop  (armature) 
in  the  direction  indicated 
by  small  crank  arrow, 
the  side  next  us  will  move 
upward,  while  the  other 
moves  downward,  so  that 
on  the  side  of  the  loop  next 
us  the  current  will  flow  to 
the  right,  toward  collecting 
ring  B,  whereas  on  the 
other  side  it  will  flow  to 


Figure  2. 


NOTE.— Strictly  speaking  it  Is  vol- 
tage (E.M.F.)  which  is  generated,  but 
my  purpose  is  served  by  the  use  of 
the  term  "current,"  which  is  less 
confusing  to  the  student. 

the  left,  away  from  the  col- 
lecting ring  A,  but  by  reason  of  the  fact  that  the  wire  is  in  the 
form  of  a  loop  the  current  flows  clear  around  the  coil,  out 
through  brush  A,  around  wire  E  to  brush  B,  and  back  into  the 
loop  again,  and  thus  we  have  the  electric  action  of  a  generator 
exemplified.  This  is  how  current  is  generated. 

But  this  is  not  all,  since  at  the  end  of  one-half  revolution  the 
two  sides  of  the  coils  will  have  changed  place,  and  the  current, 
still  moving  in  the  same  direction  with  relation  to  the  magnet, 
will  then  be  flowing  away  from  ring  A,  and  toward  ring  B, 
which,  as  you  will  readily  see,  means  the  reversal  of  the  current 
within  the  wire  coil  itself,  as  well  as  in  outside  circuit  B,  and 
this  reversal  must,  perforce,  occur  with  every  half  revolution  of 
the  coil,  or  armature.  In  considering  this  matter,  bear  carefully 
in  mind  the  fact  that,  with  relation  to  the  poles  of  the  magnet, 
the  current  will  always  flow  in  the  direction  indicated  by  the 


10 


MOTION    PICTURE    HANDBOOK 


arrows;  also  remember  that  this  wire  coil  merely  represents  one 
coil  out  of  the  many  wound  upon  the  armature  of  a  generator, 
but  that  the  electrical  action  in  all  armature  coils  is  essentially 
the  same  as  that  of  the  one  described. 

I  think  after  a  careful  study  of  the  foregoing  you  will 
readily  grasp  the  idea,  and  understand  how  current  is  gener- 
ated in  an  armature  coil;  also  why  the  current  in  the  armature 
of  a  dynamo  constantly  reverses  its  direction,  or,  in  other 
words,  is  "alternating." 

The  current  in  the  armature  of  all  generators  reverses  its 
direction  as  above  set  forth,  though  in  multipolar  dynamos 
(generators  having  more  than  two  poles)  it  is  reversed  every 
time  the  coil  passes  from  the  influence  of  one  set  of  poles 
into  the  influence  of  another  set  of  poles,  which  may  occur 
several  times  to  each  revolution  of  the  armature. 


Figure  3. 


FOR    MANAGERS    AND   OPERATORS  11 

All  this  is  just  as  true  of  direct  current  generators  as  it  is  of 
alternating  current  generators,  but  in  the  case  of  the  direct 
current  dynamo  the  alternating  current  generated  in  the 
armature  itself  is  rectified  by  what  is  known  as  the  "commu- 
tator," so  that  the  current  on  the  outside  circuit  flows  constantly 
in  one  direction,  or,  in  other  words,  is  direct  current.  As  a 
matter  of  fact  all  electric  dynamos  generate  alternating  cur- 
rent in  their  armatures.  A  study  of  what  has  gone  before 
will  show  that  this  could  not  possibly  be  otherwise. 

Fig.  3  is  an  illustration  of  a  simple  form  of  dynamo,  tech- 
nically known  as  a  "two-pole,  shunt-wound"  machine.  N  is 
the  north  and  b  is  the  south  pole  of  its  "field  magnet."  The 
dotted  lines  between  its  pole  pieces  represent  lines  of  magnetic 
force,  and  its  voltage  and  capacity  will  depend  upon  (a)  the 
number  of  lines  of  magnetic  force  passing  between  the  two 
poles,  or,  in  other  words,  the  "strength  of  the  magnetic  field," 
or,  in  other  words,  the  "density  of  the  magnetic  flux"  per 
square  inch  of  the  surface  of  the  pole  pieces  on  the  side  next 
to  the  armature;  (b)  the  number  of  coils  of  wire  the  armature 
contains,  and,  (c)  the  rotary  speed  of  the  armature.  Of 
course,  there  are  other  details  of  construction,  such  as  the 
kind  of  iron  in  the  magnets,  size  of  magnets,  kind  of  arma- 
ture core,  etc.,  which  are  of  great  importance,  but  these  items 
only  have  to  do  with  the  efficiency  of  the  machine,  not  its 
operating  principle. 

The  magnet  of  this  type  of  machine  is  what  is  termed  a 
"permanent  magnet."  That  is  to  say,  the  iron  of  its  magnets 
remains  magnetized  after  the  armature  has  come  to  rest.  The 
slight  magnetism  retained  by  the  iron  after  the  armature  has 
stopped  is  termed  "residual  magnetism,"  and  it  is  this  residual 
magnetism  which  enables  the  machine  to  start  up  without 
having  its  magnets  excited  from  an  outside  source.  The 
residual  magnetism  is,  however,  very  weak,  and,  in  practice, 
running  at  normal  speed,  the  average  dynamo  would  generate 
five  or  at  the  most  ten  volts  when  operating  merely  on  the 
residual  magnetism  of  its  field  magnet,  which  would  be  totally 
inadequate  for  commercial  purposes. 

Now  the  voltage  generated  by  the  armature  will  depend 
upon  the  number  of  lines  of  magnetic  force  which  the  con- 
ductors upon  that  armature  cut  per  second.  The  number  of 
lines  of  force  cut  per  second,  and  in  consequence  the  voltage 
could,  of  course,  be  increased  by  increasing  the  number  of 
coils  on  the  armature,  but  in  practice  this  would  require  an 
armature  of  huge  proportions.  The  same  effect  could  be  had 
by  increasing  the  speed  of  the  armature,  but  there,  too,  is  a 


12  MOTION    PICTURE   HANDBOOK 

limit,  and  high  speeds  are  objectionable.  It  therefore  follows 
that  the  really  practical  method  of  increasing  the  number  of 
lines  of  force  cut  per  second  is  to  establish  the  speed  of  the 
armature  and  the  number  of  coils  thereon,  and  then  increase 
the  density  of  the  magnetic  field  until  the  desired  result  is  at- 
tained, and  this  is  the  method  which  is  adopted.  It  is  done 
as  follows:  Examining  Fig.  3  you  will  observe  there  is  a  wire 
coil  around  the  top  part  of  the  poles  of  the  field  magnet.  This 
wire  connects  with  one  brush,  passes  thence  to  one  end  of  coils 
of  resistance  wire,  known  as  the  "field  rheostat,"  and  from  the 
other  end  of  these  coils  to  and  several  times  around  one  of  the 
poles  of  the  field  magnet,  across  the  air  gap  to  and  several  times 
around  the  other  pole  of  the  field  magnet,  and  thence  to  the 
opposite  brush.  This  circuit  is  known  as  the  "field  circuit" 
or  "shunt  field  circuit." 

Now,  it  is  a  well  known  fact  if  a  wire  be  wound  around  the 
poles  of  a  magnet  and  an  electric  current  be  passed  through 
the  coil  thus  formed,  the  strength  of  the  magnet  will  be  in- 
creased; in  other  words,  the  magnetic  field  between  its  poles 
will  be  made  more  dense  and  powerful,  or,  in  other  words, 
the  lines  of  magnetic  force  or  the  magnetic  flux  will  be  made 
greater;  and  this  will  continue  as  the  current  is  increased  until 
the  point  of  saturation  (iron  is  said  to  be  "saturated"  with 
magnetism  when  it  will  receive  no  more)  is  reached. 

As  applied  to  the  dynamo,  the  operation  of  the  field  circuit 
is  as  follows:  In  starting  up,  the  armature  is  revolved  and 
brought  up  to  speed  by  an  engine  or  some  other  source  of 
power.  The  armature  coils  cutting  through  the  weak  field 
created  by  the  residual  magnetism  generate  a  slight  voltage, 
and,  the  resistance  of  the  field  rheostat  (See  Fig.  3)  having 
first  been  eliminated  by  means  provided,  a  current  is  set  up 
in  the  field  coils,  which,  in  compliance  with  the  facts  before 
set  forth,  instantly  increases  the  strength  of  the  magnetic 
field,  and  thus  the  armature  coils  are  made  to  cut  a  greater 
number  of  lines  of  magnetic  force  per  second  and  the  voltage 
is  increased,  and  so  on  until  the  voltage  at  which  the  machine 
is  intended  to  operate  has  been  reached,  whereupon  the  handle 
of  the  field  rheostat  is  moved,  and  resistance  is  cut  into  the 
field  circuit  in  such  amount  as  will  just  regulate  the  flow  of 
current  in  the  field  circuit  to  the  value  which  will  hold  the 
strength  of  the  magnet  field  at  a  point  which  will  cause 
the  armature  to  cut  just  enough  lines  of  force  per  second  to 
maintain  the  desired  voltage. 

It  will,  of  course,  be  readily  seen  that  as  the  load  on  the 
generator  changes  an  alteration  of  the  strength  of  the  magnetic 


FOR   MANAGERS   AND   OPERATORS  13 

field  will  be  necessary,  or,  in  other  words,  variations  in  load 
of  the  generator  will  require  the  altering  of  the  amount  of 
resistance  in  its  field  circuit,  which  in  some  dynamos  is  ac- 
complished automatically,  while  in  others  it  must  be  done 
by  hand. 

All  the  foregoing  applies  in  practice  to  the  shunt-wound 
dynamo,  and  also  very  largely  to  the  compound  wound  dyna- 
mo, but,  no  matter  what  the  type  of  generator  may  be,  the 
principle  set  forth  holds  good. 

The  current  for  the  field  circuit  is  taken  direct  from  the 
armature  of  the  generator,  but  this  comprises  a  very  small 
fraction  of  the  total  output  of  the  machine — considerably  less 
than  10  per  cent. 

It  is  not  designed  to  do  more  than  give  a  comprehensive 
understanding  of  the  method  by  which  electricity  is  generated. 
There  are  many  excellent  works  on  dynamo  action  and  con- 
struction, which  may  be  consulted  at  the  public  library  of 
your  city  and  the  student  can  go  as  far  as  he  likes  in  such 
matters.  In  this  work  I  can  only  find  space  for  such  practical 
things  with  relation  to  dynamos  as  may  be  expected  to  be  of 
direct  assistance  to  operators  who  are  obliged  to  manage  and 
care  for  generators  or  a  motor  generator  set. 

THE  DIFFERENCE  BETWEEN  ALTERNATING  AND 
DIRECT  CURRENT 

Direct  current,  commonly  called  "D.  C.,"  acts  continuously 
in  one  direction,  presumably  from  positive  to  negative.  The 
electrical  impulse  or,  putting  it  another  way,  the  flow  of  cur- 
rent is,  theoretically,  outward  from  the  positive  brush  of  the 
generator  to  the  positive  wire  of  the  circuit,  along  that  wire 
to  and  through  the  various  lamps,  motors,  etc.,  to  the  negative, 
and  back  on  the  negative  wire  of  the  circuit  to  the  negative 
brush  of  the  generator.  Direct  current  is  very  seldom  of 
higher  voltage  than  500,  since  above  that  pressure  it  becomes 
exceedingly  difficult  to  effectively  insulate  the  commutator 
bars  of  the  generator  from  each  other.  Another  reason  why 
we  do  not  find  D.  C.  at  high  voltage  lies  in  the  fact  that  after 
leaving  the  generator  its  pressure  cannot  be  raised  without 
the  use  of  machines  having  moving  parts,  which  is  impractical 
by  reason  of  the  expense  of  installation  and  operation,  as  well 
as  the  necessary  loss  inherent  in  such  a  device. 

Alternating  current  is  commonly  known  by  the  abbrevia- 
tion "A.  C."  As  has  already  been  set  forth,  the  current  in  the 
armature  of  all  generators  is  alternating;  that  is  to  say,  the 


14  MOTION    PICTURE    HANDBOOK 

current  in  the  armature  coils  constantly  reverses  its  direction, 
and  "alternating  current"  (A.  C.)  is  nothing  more  or  less  than 
the  unrectified  current  which  is  sent  out  on  the  circuit  just  as 
it  is  generated  in  the  armature  coils  of  the  dynamo,  so  that 
the  current  in  the  whole  circuit  reverses  its  direction  as  often 
as  the  current  is  reversed  in  the  armature  coils  of  the  dynamo. 

There  are  several  reasons  why  A.  C.  is  very  largely  used, 
the  main  one  being  the  fact  that  it  may  be  generated  at  rela- 
tively high  pressure;  also  the  pressure  (voltage)  may  be 
readily  increased  or  reduced  after  the  current  has  left  the 
dynamo  and  this  may  be  accomplished  by  means  of  a  very 
simple  device  known  as  a  "transformer,"  which  has  no  mov- 
ing parts,  requires  practically  no  care  or  attention,  lasts  in- 
definitely if  not  overloaded,  and  accomplishes  its  work  of  in- 
creasing or  decreasing  the  voltage  with  comparatively  little  loss 
of  energy. 

The  advantage  of  high  voltage  lies  in  the  fact  that  while  a 
wire  of  given  size  is  rated  at  a  certain,  definite  number 
of  amperes  and  no  more  (See  Table  1,  Page  42),  it  will  carry 
those  amperes  at  any  voltage.  Electric  energy,  by  which  is 
meant  the  ability  of  the  current  to  perform  work,  is  measured 
in  "watts."  One  watt  is  equal  to  1/746  of  a  horse  power.  It 
therefore  follows  that  746  watts  is  equal  to  1  horse  power. 
Watts  are  found  by  multiplying  volts  by  amperes,  thus:  5 
amperes  at  110  volts  equals  (5  X  HO)  watts.  Horse  power 
equals  volts  multiplied  by  amperes  divided  by  746. 

Referring  to  Table  1,  Page  42,  we  find  that  a  No.  6  rubber 
covered  wire  must  not  be  allowed  to  carry  more  than  50  am- 
peres of  current.  Now  suppose  .we  have  a  No.  6  wire  carry- 
ing 50  amperes  at  110  volts:  110X50=5500  watts,  which 
divided  by  746  (watts  in  a  horse  power)  gives  us  approx- 
imately iy-2.  h.p.  as  the  limit  of  power  which  can  be  conveyed 
on  a  No.  6  r.c.  wire  charged  at  110  volts  pressure.  On  the 
other  hand,  suppose  we  have  the  same  No.  6  r.c.  wire  carry- 
ing 50  amperes  at  2000  volts  pressure.  We  then  have  2000  X 
50  =  100,000  watts,  which  divided  by  746  equals  almost  135  h.p., 
now  being  conveyed  over  a  No.  6  r.c.  wire  which  was  loaded 
to  capacity  with  7^2  'h.p.  when  the  pressure  was  110  volts. 

From  the  foregoing  it  will  readily  be  seen  that  there  is 
enormous  saving  in  copper  (wire  diameters)  effected  by  using 
high  voltage.  This  is  a  particularly  important  item  if  the 
power  (current)  is  to  be  conveyed  any  considerable  distance. 
To  convey  1000  h.p.  five  miles  by  means  of  110  volts  pressure 
would  entail  an  enormous  outlay  for  wires  of  large  size,  since 


FOR    MANAGERS    AND    OPERATORS  15 

it  would  require  nearly  7000  amperes,  whereas  with  the  current 
at  10,000  volts  only  about  75  amperes  would  be  necessary. 

As  has  been  said,  A.  C.,  unlike  D.  C.,  does  not  flow  con- 
tinuously in  one  direction,  but,  quite  the  contrary,  flows  in 
one  direction  and  then  reverses  and  flows  in  the  opposite.  In 
other  words,  the  current  flows  one  way  for  a  small  fraction  of 
a  second  and  then  reverses  itself  and  flows  in  the  opposite 
direction  for  an  equal  space  of  time,  the  period  of  flow  in 
either  direction  varying  from  1/50  to  1/266  of  a  second,  accord- 
ing to  the  way  the  generator  is  designed.  Two  periods  of 
flow — that  is  to  say,  the  period  during  which  the  current 
flows  in  one  direction  and  reverses  itself  and  flows  back — 
are  called  a  "cycle."  See  definition  of  cycle,  page  22. 

Alternating  current  dynamos  may  be  designed  to  pro- 
duce current  of  any  given  number  of  cycles  per  second,  the 
determining  factor  being  the  use  the  current  is  to  be  put  to. 
Where  light  only  is  produced,  the  current  frequency  (number 
of  cycles  per  second)  may  be  quite  high;  sometimes  as  much 
as  133  cycles  (266  alternations)  per  second;  but  cf  late  years 
the  use  of  current  frequency  in  excess  of  60  has  been  almost 
entirely  abandoned. 

Where  the  current  generated  is  to  be  used  entirely  for 
power  purposes  a  low  frequency  is  much  preferred,  for  the 
reason  that  it  is  more  economical  for  driving  motors.  Power 
current  runs  as  low  as  25  cycles  per  second,  whicL  is  the  ideal 
current  to  apply  to  motors.  Twenty-five  cycles  per  second, 
however,  is  unsatisfactory  for  incandescent  or  arc  lighting, 
since  the  alternations  are  so  far  apart  that  there  is  a  notice- 
able flicker  in  the  light.  Light  and  power  companies  long  ago 
discovered  the  fact  that  60-cycle  current  produces  very  satis- 
factory results  in  lighting,  and  is  at  the  same  time  fairly 
economical  for  power  purposes.  For  this  reason  practically 
ajl  generators  designed  to  provide  both  light  and  power  are 
what  is  known  as  60-cycle.  machines. 

It  is  essential  that  the  operator  get  a  clear  understanding 
of  these  things,  since  more  and  more  they  are  called  upon  to 
handle  motors  and  generators,  and  moreover  in  some  localities 
and  under  some  conditions  problems  arise  which  can  only  be 
solved  by  one  conversant  with  this  subject.  The  action  f 
alternating  current  is  usually  expressed  by  diagram,  such  as 
that  shown  in  Fig.  4,  and  I  will  now  try  to  help  you  to 
understand  how  to  trace  out  the  real  meaning  of  such  dia- 
grams. Indeed,  it  is  very  necessary  that  you  do  understand, 
because  when  one  studies  matters  electrical,  he  is  constantly 


16  MOTION    PICTURE    HANDBOOK 

confronted  with  diagrams  of  this  character,  and  if  unable  to 
trace  out  their  meaning  is  greatly  handicapped  in  his  study. 

Let  us  consider  Fig.  4.  In  its  length  the  horizontal  line 
represents  time,  and  in  its  position  with  relation  to  the  trian- 
gles above  and  below  it  represents  zero  voltage,  or,  in  other 
words,  no  voltage,  or,  in  other  words,  it  represents  the  point 
at  which  the  alternations  of  the  current  are  completed  and 
the  voltage  and  amperage  are  both  at  zero. 

From  0  to  1  represents  the  time  of  one  alternation,  which 
with  60-cycle  current  would  be  1/120  of  a  second;  the  rise  and 
fall  of  voltage  in  that  alternation  being  represented  by  the 


Figure  4. 

triangular  line  above  the  horizontal  line  which  leaves  0, 
mounts  upward  and  comes  back  down  to  1.  The  vertical 
column  of  figures  represents  voltage.  Turn  back  to  Fig.  2  and 
examine  it  and  the  text  matter  dealing  therewith,  so  that  the 
action  of  an  armature  coil  will  be  fresh  in  your  memory. 
Remember  that  when  the  coil  in  Fig.  2  is  in  the  position 
shown,  it  is  generating  maximum  voltage,  and,  conversely, 
when  standing  straight  up  and  down  it  is  in  what  we  call  the 
"neutral  plane,"  and  for  an  infinitesimal  fraction  of  a  second 
is  generating  nothing.  Now,  coming  back  to  our  diagram, 
Fig.  4,  where  the  line  of  the  triangle  leaves  and  mounts  up- 
ward, the  coil  of  the  armature  is  beginning  to  cut  lines  of 
force  in  increasing  number,  and  the  voltage  is  rising  and  con- 
tinues to  do  so  until  the  coil  is  cutting  the  maximum  lines  of 
force,  at  which  time  the  voltage  has  reached  110.  Meanwhile 
time  equal  to  half  of  an  alternation,  or,  1/120  -r-  2  =  1/240  of 
a  second,  has  elapsed.  Now  the  armature  coil,  begins  to  pass 


FOR   MANAGERS    AND    OPERATORS  17 

out  of  the  magnetic  field,  and  the  voltage  decreases  until,  fol- 
lowing the  right-hand  line  of  the  triangle  down  to  1,  it  is  at 
zero,  and  the  current  reverses.  If  we  now  follow  the  line  on 
down  on  the  left-hand  side  of  the  lower  triangle  and  back  up 
to  2,  we  will  have  traced  the  action  of  two  alternations,  or 
one  cycle  of  current,  and  during  that  time  1/60  of  a  second 
will  have  elapsed.  Now,  in  your  imagination,  draw  a  pencil 
point  from  0  to  1,  and  another  pencil  point  round  the  upper 
triangle,  and  then  continue  the  first  pencil  out  on  to  2  and 
run  the  other  pencil  point  down  around  the  lower  triangle. 
If  you  could  draw  one  pencil  point  from  0  to  2  in  1/60  of  a 
second,  and  in  the  same  length  of  time  trace  the  two  triangles, 
one  above  and  one  below  the  line,  to  2,  with  the  other  pencil 
point,  you  would  have  exactly  typified  the  action  of  one  cycle 
of  alternating  current,  both  as  to  time  and  rise  and  fall  of  vol- 
tage and  amperage. 

With  25-cycle  current,  the  action  would  be  precisely  the 
same,  except  that  from  0  to  2  would  represent  1/25  of  a  sec- 
ond, instead  of  1/60  of  a  second,  and  the  action  of  the  current 
therefore  would  be  just  that  much  slower. 

In  studying  the  above  get  the  fact  clearly  fixed  in  your 
mind  that,  while  the  action  is  almost  inconceivably  rapid,  still 
it  is  a  fact  that  with  plain,  single-phase  alternating  current,  twice 
during  each  cycle,  or  one  hundred  and  twenty  times  every  second, 
there  is  absolutely  no  voltage,  amperage,  or  anything  else  on  the 
line.  This  is  hard  for  the  mind  to  grasp,  since  it  is  very  difficult 
for  the  mind  to  accustom  itself  to  such  extreme  rapidity  of 
motion. 

The  student  may  ask:  "Well,  if  it  is  a  fact  that  there  is  no 
voltage  or  amperage  on  the  line  twice  during  each  cycle,  how 
does  it  happen  that  the  light  from  alternating  current  is  con- 
tinuous?" In  reply  I  would  say  that  the  light  is  not  contin- 
uous, but  the  action  is  so  enormously  rapid  that  the  effect  of 
one  alternation  blends  in  the  next,  so  that  with  60-cycle  current 
the  effect  is  that  of  continuous,  uninterrupted,  even  illumina- 
tion, but  if  the  current  be  25-cycle,  then  the  action  is  slow 
enough  that  the  eye  can  detect  an  uneveness  of  illumination, 
in  the  form  of  flicker,  and  that  is  why  very  low  cycle  alter- 
nating current,  while  ideal  for  power  purposes,  is  objection- 
able and  unsatisfactory  for  lighting. 

In  handling  alternating  current  we  run  into  many  complica- 
tions, one  of  which  is  the  fact  that  we  have  single-phase, 
two-phase,  and  three-phase  current  to  deal  with.  In  Fig.  4 
we  have  traced  the  action  of  alternating  current.  In  Fig.  5 
we  see,  at  A,  a  diagrammatic  representation  of  two-phase 


18 


MOTION    PICTURE    HANDBOOK 


current.  Two-phase  and  three-phase  current  is  produced 
by  a  peculiarity  of  the  winding  of  the  generator.  How- 
ever, for  the  purpose  of  a  clear  understanding,  we  will  assume 
that  we  have  two  generators,  producing  current  of  the  same 
cycle,  with  their  armatures  coupled  rigidly  together  in  such 
manner  that  when  the  current  flow  of  one  is  at  zero  the  vol- 
tage of  the  other  is  at  maximum.  We  will  thus  have  a  two- 
phase  current  delivered,  and  the  voltage  of  such  a  circuit  will 
never  be  at  zero,  since  when  the  current  generated  by  one  of 
the  machines  is  at  zero  the  other  is  at  maximum.  Now,  if  we 
couple  the  shaft  of  a  third  dynamo  to  the  shafts  of  the  other 


Figure  5. 

% 

two,  in  such  manner  that  the  voltage  rises  and  falls,  as  shown 
at  B,  Fig.  5,  we  shall  have  three-phase  current.  Two-phase 
current  ordinarily  employs  four  wires  (two  separate  circuits) 
for  its  distribution.  Its  advantage  lies  in  the  fact  that  the 
two  currents,  acting  like  the  piston  of  a  double  engine,  give 
a  steady  instead  of  an  intermittent  pull  on  the  armature  of 
motors.  Three-phase  current  requires  three  wires  for  its 
distribution.  It  is  the  ideal  system  for  transmitting  energy, 
through  any  distance,  for  power  purposes. .  It  gives  a  prac- 
tically steady  pull  on  the  motor  armature.  Neither  the  two 
nor  three  phase  systems  has  any  particular  advantage  over 
single-phase  60  cycle  current  for  lighting  purposes. 


Electrical  Terms 

IT   is  essential  that  the   operator  have   a  complete    under- 
standing of  certain  terms  used  in  connection  with  elec- 
trical work.     It  is  quite  difficult  to  impart  a  clear  under- 
standing of  some  of  the  terms,  but  we  will  nevertheless  do 
our  best  to  make  the  matter  at  least  reasonably  clear. 

Work  is  the  term  used  to  describe  the  act  of  overcoming 
resistance  through  a  certain  distance.  It  is  measured  in  foot- 
pounds. See  foot-pounds. 


FpR   MANAGERS    AND    OPERATORS  19 

Foot-pounds. — A  foot-pound  is  the  amount  of  work  done  or 
energy  consumed  in  raising  a  weight  of  one  pound  one  foot, 
or  the  equivalent,  such  as,  for  instance,  raising  one-half 
pound  two  feet,  or  raising  two  pounds  one-half  foot.  It  may 
also  be  described  as  overcoming  a  pressure  of  one  pound 
through  a  distance  of  one  foot. 

Coulomb. — The  coulomb  is  used  to  measure  the  quantity 
of  current  flowing  in  one  second.  It  is  the  number  of  ^am- 
peres of  current  passing  in  one  second.  It  is  the  product  of 
the  amperes  times  seconds,  thus: 

10  amperes  flowing  in  1  second  multiplied  by  1 
second  equals  10  coulombs;  10  amperes  flowing 
for  2  seconds  equals  20  coulombs. 

Volt-Coulomb. — The  volt-coulomb  is  the  electrical  unit  of 
work.  It  is  that  amount  of  work  performed  when  one  ampere 
of  current  flows  for  a  period  of  one  second  in  a  circuit  whose 
resistance  is  one  ohm,  when  the  pressure  is  one  volt. 

Ampere-Hour. — One  may  draw  a  certain  quantity  of  water, 
say  a  gallon,  from  a  hydrant  in  one  minute,  or  in  ten  min- 
utes, but,  regardless  of  the  time  consumed  in  drawing  the 
water,  it  is  still  one  gallon,  no  more  and  no  less.  The 
same  holds  true  in  dealing  with  electric  current.  A  certain 
given  quantity  may  be  used  in  one  minute,  or  in  ten  minutes. 
The  current  flowing  in  any  circuit  is  the  relation  of  the  quan- 
tity flowing  to  the  time  during  which  it  flows,  or,  expressed 
otherwise: 

As  has  been  said,  coulombs  equals  amperes  multiplied  by 
seconds,  or, 

2  amperes  X  10  seconds  =  20  coulombs. 
10  amperes  X    2  seconds  =  20  coulombs. 

1  ampere  X  20  seconds  =  20  coulombs,  and  so  on. 
By  the  foregoing  you  will  be  able  to  calculate  that  if  one 
ampere  flows  for  one  'hour  we  would  have  1  ampere  X  60  sec- 
onds =  60  coulombs,  and  60  coulombs  X  60  minutes  =  3600  cou- 
lombs, so  that  one  ampere  flowing  for  one  hour  equals  3600 
coulombs,  and  3600  coulombs  are,  therefore,  one  ampere- 
hour,  or  a  flow  of  2  amperes  for  one-half  hour  would  be  one 
ampere-hour,  or  a  flow  of  4  amperes  for  15  minutes  would  be 
one  ampere-hour,  since  in  either  case  3600  coulombs  would 
have  been  used. 

Ampere. — Ampere  is  the  unit  rate  of  current  flow.  It  repre-^ 
sents  the  quantity  of  current  flowing  through  a  circuit,  pre- 
cisely the  same  as  gallons  or  barrels  represent  the  quantity 
or  volume  of  water  flowing  through  a  water  pipe. 


20  MOTION    PICTURE   HANDBOOK 

Operators  should  carefully  consider  the  distinction  between 
the  ampere  and  the  coulomb.  The  term  coulomb  is  not  much 
used,  but  it  is  nevertheless  one  of  much  importance,  since  it 
measures  the  quantity  of  current  passing  in  a  given  time. 

The  ampere  is  such  a  rate  of  flow  as  would  transmit  one 
coulomb  per  second  through  a  resistance  of  one  ohm,  under  a 
pressure  of  one  volt;  a  current  of  such  strength  as  would 
deposit  .005084  grain  of  copper  per  second. 

Volt — The  volt  is  the  unit  of  electric  pressure.  It  is  the 
electro-motive  force  induced  in  a  conductor,  usually  an  arma- 
ture coil,  which  is  cutting  100,000,000  lines  of  magnetic  force 
per  second.  It  is  the  term  used  to  designate  the  strength  of 
the  affinity  of  one  wire  of  an  electric  circuit  to  and  for  the 
other  wire.  It  is  the  term  used  to  designate  and  describe  the 
intensity  of  electrical  action.  It  is  the  term  used  to  designate 
that  quality  or  property  of  the  electric  current,  or  electric 
action,  which  corresponds  to  pressure  in  a  steam  boiler,  or  in 
a  water  pipe. 

Ohm. — Ohm  is  the  unit  of  resistance.  It  is  the  term  used  to 
designate  and  measure  the  opposition  offered  to  the  flow  of 
electric  current.  It  is  the  amount  of  resistance  offered  by  a 
column  of  mercury  106  centimeters  in  length,  having  an  area 
of  cross  section  of  one  square  millimeter,  at  0  degrees  centi- 
grade, or  32  degrees  F.  This  is  the  established  international 
value  of  the  ohm,  designated  as  the  "Legal  Ohm." 

Watt. — Watt  is  the  unit  of  power.  It  is  obtained  by  multi- 
plying volts  by  amperes:  1  volt  X  1  apmere  =  1  watt,  hence, 
10  amperes  at  110  volts  would  be,  100  X  10=  1100  watts;  746 
watts  equal  1  horse  power  (h.p.).  See  kilowatt.  See  watt- 
hour. 

Kilowatt.- — Kilowatt  is  merely  a  term  of  convenience,  mean- 
ing 1000  watts.  It  is  1000  -f-  746  =  1.34  ihorse  power. 

Watt-Hour. — One  watt-hour  represents  the  amount  of  work 
performed  by  one  ampere  of  current  at  one  volt  pressure  dur- 
ing a  period  of  one  hour,  hence,  4  amperes  at  110  volts  would 
be  440  watts,  and  when  that  amount  of  energy  has  been  ex- 
pended for  a  period  of  one  hour  it  would  be  440  watt-hours. 

Horse-Power. — One  horse-power  (h.p.)  equals  33,000  foot- 
pounds of  work  per  minute.  It  is  the  theoretical  amount  of 
work  one  strong  draft  horse  is  supposed  to  perform  if  a  block 
and  tackle  be  attached  to  a  weight  of  33,000  pounds  and  the 
tackle  be  of  such  proportion  that  the  horse  can,  by  exerting 
his  full  strength,  just  raise  the  33,000  pounds  one  foot  while 
walking  outward  pulling  on  the  rope  for  a  period  of  one  min- 
ute. Under  these  conditions  one  horse-power  has  been  ex- 


FOR   MANAGERS    AND    OPERATORS  21 

erted  during  that  minute.  That  is  the  theory  of  the  thing. 
One  horse-power-hour  is  the  amount  of  work  exerted  by  one 
horse  during  one  hour,  or  by  60  horses  during  one  minute,  or 
by  3600  horses  during  one  second.  In  electrics  746  watts  is 
supposed  to  represent  the  raising  of  33,000  pounds  one  foot  in 
one  minute,  or,  in  other  words,  one  horse  power.  The  unit 
was  established  as  follows:  1  watt  is  equivalent  to  1  joule 
per  second  (the  joule  is  the  practical  C.G.S.  unit  of  electrical 
energy.  One  joule  is  equal  to  .73734  of  a  foot-pound,  or,  .00134 
h.p. -seconds;  it  is  the  quantity  of  electric  energy  necessary 
to  raise  the  potential  of  one  coulomb  of  electricity  one  volt  in 
pressure)  or  60  joules  per  minute,  and  1  joule  is  equal  to 
.73734  of  a  foot-pound,  therefore  60  joules  =  60  X  .73734  = 
44.24  foot-pounds.  Now,  since  one  horse-power  equals  33,000 
foot-pounds  per  minute  the  electrical  equivalent  would  be 
33,000^-44.24  =  746  watts. 

Resistance  is  that  property  of  an  electrical  conductor  by 
which  it  resists  the  flow  of  electric  current.  It  is  quite  similar 
in  its  effect  on  electric  current  to  the  opposition  water  en- 
counters in  flowing  through  a  pipe  by  reason  of  friction  with 
the  walls  of  the  pipe. 

Polarity. — Polarity  is  the  difference  in  condition  between 
the  positive  and  the  negative  electrodes  of  a  battery,  or  of  two 
wires  attached  to  the  positive  and  the  negative  electrodes  of 
a  battery.  It  is  the  difference  in  condition  between  the  two 
terminals  of  a  working  dynamo,  or  between  the  wires  attached 
thereto.  It  may  be  described  as  representing  the  ability  of 
the  two  battery  electrodes,  dynamo  terminals,  or  wires  at- 
tached thereto,  to  perform  work.  Positive :  from  which  electric 
impulse  comes  or  "flows."  Negative:  opposite  of  positive. 

Short  Circuit. — The  term  applied  to  a  direct,  accidental  cur- 
rent-carrying connection  between  two  wires  of  opposite 
polarity,  by  means  of  which  the  current  is  enabled  to  skip  a 
portion  of  its  appointed  path. 

Shunt  Circuit. — A  subsidiary  or  secondary  circuit  on  any 
part  of  a  main  circuit,  by  means  of  which  a  portion  of  the 
current  leaves  the  main  circuit  and  flows  through  the  sub- 
sidiary or  secondary  circuit,  as,  for  instance,  the  field  magnet 
circuit  in  Fig.  3,  page  10. 

Commutator. — A  device  attached  to  the  armature  of  a  dy- 
namo by  means  of  which  the  alternating  current  generated  in 
the  armature  coils  is  changed  into  direct  current  for  delivery 
to  the  outside  circuit. 


22  MOTION    PICTURE    HANDBOOK 

Direct  Current.— Current  which  flows  continually  in  one 
direction. 

Alternating  Current. — Current  which  flows  alternately  in 
one  direction  and  then  in  the  opposite,  the  time  of  the  flow  in 
either  direction  varying  from  1/50  of  a  second  to  1/226  of  a 
second,  according  to  the  construction  of  the  generator. 

Conductor. — A  wire  or  metal  bar  used  to  convey  electric 
current. 

Cycle. — Events  following  each  other  in  regular  succession. 
One-half  the  number  of  changes  in  direction  of  alternating 
current  per  second.  Two  complete  alternations  of  alternating 
current. 

Dimmer. — An  adjustable  choke  or  resistance  coil  used  for 
increasing  or  decreasing  the  resistance  in  an  incandescent 
circuit  gradually,  so  that  the  incandescent  lamps  attached 
thereto  will  be  extinguished  or  lighted  gradually.  An  adjust- 
able rheostat  for  use  on  incandescent  light  circuits. 

Electric  Motive  Force. — Another  name  for  voltage,  and  the 
one  commonly  employed  in  text  books. 

Ground. — A  connection  between  wires  of  opposite  polarity 
through  the  ground,  having  resistance  low  enough  to  allow 
current  to  pass  from  one  wire  to  the  other. 

Static  Electricity.— A  form  of  electricity  which  is  generated 
by  friction. 

Main  Feeder. — The  street  circuit  entering  a  district  to 
which  feed  wires  supplying  the  various  streets  are  attached. 

Street  Mains. — Feed  wires  supplying  individual  house  mains. 

Electro  Magnetic  Field. — The  field  produced  by  an  alter- 
nating electric  current  or  by  an  electric  magnet. 

Magnetic  Field. — That  region  of  magnetic  influence  which 
surrounds  the  poles  of  a  magnet  or  wire  carrying  A.  C. 

Fuse. — A  short  length  of  wire  interposed  in  an  electric  cur- 
rent, the  same  being  of  some  alloy  which  will  melt  (thus 
breaking  the  circuit  and  stopping  the  flow  of  current)  at  a 
temperature  much  less  than  that  necessary  to  raise  the  tem- 
perature of  a  copper  circuit  wire  to  the  danger  point.  Fuses 
usually  melt  at  less  than  300  degrees  F. 

Galvanized  Iron  Wire. — An  iron  wire  coated  with  zinc,  in 
order  to  resist  the  action  of  corrosion. 

Graphite. — A  condition  of  carbon  in  which  it  becomes  an 
excellent  lubricant,  able  to  withstand  very  high  temperature. 


FOR   MANAGERS    AND   OPERATORS  23 

In  this  condition  it  forms  the  "lead"  of  the  ordinary  lead 
pencil. 

Induction. — The  influence  which  a  mass  of  iron  charged 
with  alternating  current  exercises  upon  surrounding  metallic 
bodies,  without  having  any  actual  metallic  connection  there- 
with. 

Insulation. — The  employment  of  any  material  having  such 
high  resistance  that  electric  current  is  unable  to  pass  through 
to  the  earth,  or  other  current  carrying  substance,  and  thus 
reach  a  wire  of  opposite  polarity.  Rubber,  porcelain  and 
glass  are  examples  of  insulating  materials. 

Magnetic  Saturation. — That  point  at  which  the  power  of  a 
magnet  cannot  be  further  increased. 

Torque. — That  force  which  tends  to  produce  a  rotary  move- 
ment around  an  axle,  as  the  pulling  or  rotating  of  an  electric 
motor's  armature  upon  its  shaft.  The  force  applied  to  the 
rim  of  a  dynamo  pulley  by  a  belt.  Turning  force. 

Transformer. — An  induction  coil  by  means  of  which  the  vol- 
tage of  a  circuit  may  be  changed  without  materially  altering 
its  wattage.  A  step-up  transformer  is  one  which  transforms 
a  current  of  given  amperage  and  voltage  to  a  current  of  less 
amperage  and  higher  voltage.  A  step-down  transformer  is 
one  which  transforms  a  current  of  given  amperage  and  vol- 
tage to  a  current  of  less  voltage  and  higher  amperage. 

Ampere  Turn. — A  unit  of  magneto-motive  force  equal  to 
the  force  resulting  from  the  effect  of  one  ampere  passing 
around  a  single  turn  of  a  coil  of  wire. 

Voltmeter. — Ah  instrument  by  means  of  which  the  voltage 
or  electro-motive  force  of  a  circuit  is  measured. 

Ammeter. — An  instrument  by  means  of  which  the  current 
flow  in  a  circuit  is  measured  in  amperes. 

Wattmeter. — An  instrument  by  means  of  which  the  power 
being  consumed  in  a  circuit  is  measured  in  watts. 

Current  Frequency. — The  number  of  cycles  per  second. 

Efficiency. — The  term  used  in  describing  the  loss  inherent 
in  transformers,  motors,  generators,  generator  sets,  etc.  Elec- 
trically it  is  the  relation  of  the  wattage  taken  from  the  line  to 
the  wattage  actually  employed  in  the  work  in  hand.  For  in- 
stance: If  a  motor  takes  3000  watts  from  the  line  and  only 
exerts  a  pull  on  the  thing  it  is  driving  equal  to  2000  watts, 
then  its  efficiency  would  be  the  percentage  found  by  dividing 
2000  by  3000,  and  2000-^3000  =  .666  or  662/3  per  cent. 


24  MOTION    PICTURE    HANDBOOK 

Circuit. — The  term  commonly  applied  to  wires  of  opposite 
polarity  to  which  are  attached  other  power  consuming  circuits 
or  lamps,  motors,  etc. 

Synchronism. — Synchronism  is  the  term  used  to  describe 
the  action  of  A.  C.  alternations  with  relation  to  each  other. 
Synchronism  is  sometimes  referred  to  by  electricians  as  "keep- 
ing step."  It  means  that  where  two  or  more  alternating  cur- 
rents are  coupled  together,  as  in  two  or  three  phase  current, 
their  voltage  values  must  rise  and  fall  constantly  with  fixed 
relation  to  each  other,  as  shown  in  Fig.  4,  Page  16.  In  order 
to  produce  two  or  three  phase  current  the  voltage  values  must 
remain  absolutely  in  step  or  synchronism  with  each  other. 
When  a  motor  is  run  in  synchronism  with  a  generator  it 
means  that  the  voltage  value  of  the  alternations  in  the  arma- 
ture of  the  motor  arc  and  must  remain  absolutely  identical 
with  the  voltage  value  of  the  alternations  in  the  armature  of 
the  generator.  Once  you  grasp  the  real  meaning  of  Fig.  5 
the  understanding  of  synchronism  will  be  easy,  therefore 
study  Fig.  5. 


An  Explanation  of  Electrical  Terms, 

I  HAVE  given  you  the  definition  of  certain  electrical  terms 
which  the  operator  is  likely  to  come  into  contact  with  in 
his  work.     In  order  to  convey  a  more  complete  under- 
standing of  the  true  meaning  of  certain  ones  of  these  terms, 
however,  something  more  than  a  mere  definition  is  necessary, 
therefore  1  shall  elaborate  by  amplifying  certain  definitions 
in  the  form  of  an  explanation. 

Polarity. — Polarity  and  potential  mean  the  same  thing. 
When  a  wire  is  attached  to  one  terminal  of  a  working  dynamo 
and  another  wire  is  attached  to  the  opposite  terminal  of  the 
same  dynamo  there  is  an  electrical  condition  in  these  wires 
which  enables  them  to  perform  work,  or,  more  correctly,  to 
cause  a  motor  to  which  they  are  attached  to  perform  work,  or 
cause  a  lamp  to  which  they  are  attached  to  give  off  light.  This 
electrical  condition  is  called  "polarity,"  or  "potential."  It  is 
the  affinity  one  wire  of  an  electric  circuit  has  for  the  other 
wire  of  this  circuit.  It  represents  the  inclination  of  the  cur- 
rent to  flow  from  one  wire  to  the  other  wire,  and  this  inclina- 
tion is  so  strong  that  in  order  to  pass  from  one  wire  to 
the  other  the  current  will  perform  labor,  and  lots  of  it.  When 
dealing  with  direct  current  one  wire  is  always  positive  and 


FOR    MANAGERS    AND   OPERATORS  25 

the  other  is  always  negative;  when  dealing  with  alternating 
current  each  wire  is  alternately  positive  and  negative  many 
times  each  second. 

Voltage  (E.M.F.). — Electric  current  may  be  said  to  have 
both  pressure  and  volume,  and  in  its  action  in  both  these  re- 
spects, as  well  as  with  regard  to  friction,  electricity  is  very 
similar  to  and  may  be  compared  with  water  or  steam.  We 
must,  however,  carefully  remember,  when  using  these  com- 
parisons, that  they  only  hold  good  as  applied  to  the  laws  of  elec- 
trical action  which  have  been  determined  by  experiment.  In 
other  words,  the  similarity  between  electricity  and  water  or 
steam  exists  only  in  their  similarity  of  action.  Water  may  be 
perceived  by  the  senses;  we  can  feel  it  and  watch  its  action, 
whereas  electricity  is  an  absolutely  impalpable  substance, 
which  cannot  be  perceived  by  any  sense  except  that  of  touch, 
and  even  then  it  cannot  be  felt  except  through  the  "shock" 
occasioned  by  its  passing  over  the  tissues  of  the  body.  (We 
can  see  electric  light,  yes,  but  that  is  only  the  effect  of  the 
current,  not  the  current  itself.) 

Voltage  corresponds  in  effect  or  in  its  action  to  the  pressure 
of  water  in  a  pipe,  or  to  the  pressure  of  steam  in  a  boiler.  A 
dry  battery,  such  as  is  used  for  electric  bells,  has  a  pressure  of 
approximately  one  volt,  and  it  imparts  that  pressure  to  wires 
connected  to  its  terminals,  so  that  if  you  attach  two  wires  to 
such  a  battery  they  will,  at  any  portion  of  their  length,  have 
a  pressure  of  one  volt.  Now,  if  you  take  a  second  battery 
and  connect  its  zinc  with  the  carbon  of  the  first  battery  by 
means  of  a  short  piece  of  wire,  and  then  attach  'two  other 
wires  to  the  two  remaining  binding  posts,  you  will  have  what 
is  known  as  "series"  connection,  and  a  resultant  pressure  of 
two  volts  between  the  two  wires.  A  third  battery  connected 
in  series  would  raise  the  pressure  to  three  volts,  and  so  on, 
indefinitely.  Instead  of  using  batteries  for  producing  light 
and  power,  which  would  be  entirely  impractical,  we  use  a 
machine  called  a  dynamo,  each  one  of  which  is  designed  and 
built  to  produce  a  certain  voltage,  which  may  be  anywhere 
from  one  to  five  hundred  volts  D.  C,  or  from  one  to  six 
thousand  A.  C. 

Remember  that  voltage  corresponds  to  pressure,  and  is 
similar  in  its  action  to  pressure  in  a  steam  boiler,  but  that 
voltage  acts  only  between  the  positive  and  negative  wires  of 
the  dynamo  which  generated  it,  and  that  the  positive  attached 
to  one  generator  has  no  affinity  or  attraction  to  or  for  the 
negative  attached  to  another  dynamo,  or  for  the  ground,  ex- 
cept as  it  offers  a  path  to  the  negative  of  the  generator  to 


26  MOTION    PICTURE    HANDBOOK 

which  the  positive  is  attached.  Get  this  fact  firmly  fixed  in 
your  mind.  Ninety-nine  non-electricians  out  of  every  hundred 
believe  current  generated  by  a  dynamo  seeks  to  escape  into 
the  ground.  This  is  not  so,  except  as  the  ground  offers  a  path 
between  two  wires  of  opposite  polarity.  If  the  positive  or 
negative  side  of  a  dynamo  generating  5000  volts  be  thoroughly 
and  completely  insulated  (never  actually  the  fact  in  practical 
work)  you  could  stand  on  wet  ground  and  handle  the  bare 
wire  of  the  other  side  with  your  bare  hands  in  perfect  safety. 

Ampere. — Ampere  is  the  term  used  to  denote  quantity.  It 
represents  the  volume  of  current  flowing  through,  or  along  a 
wire,  just  as  gallons  or  barrels  represent  the  quantity  of 
water  flowing  through  a  pipe,  or  cubic  inches  the  volume  of 
steam  flowing.  As  a  matter  of  fact  we  do  not  actually  know 
that  anything  flows  in  or  along  the  wire  of  an  electric  circuit. 
Eminent  electricians  say  there  is  an  actual  flow;  other  equally 
eminent  electricians  say  there  is  not,  but  that  what  we  con- 
sider as  current  flow  is  really  a  "molecular  bombardment." 
With  these  highly  technical  questions,  however,  we  have 
nothing  to  do.  For  our  purpose  it  is  sufficient  to  say  that  current 
flows  along  the  wire,  just  exactly  as  water  flows  in  a  pipe.  The 
work  performed  is  accomplished  by  the  voltage  or  pressure 
working  through  the  amperage  or  volume,  and  it  is  the 
pressure  or  voltage  which  is  consumed — never  the  amperes. 
Therefore,  the  higher  the  voltage  or  pressure,  the  greater 
amount  of  work  a  given  volume  of  current  can  perform.  For 
instance:  If  you  supply  a  steam  engine  with  steam  at  fifty 
pounds'  pressure  it  will  consume  a  certain  given  quantity  or 
volume  of  steam  to  each  stroke  of  the  piston,  according  to  the 
cubic  capacity  of  the  cylinder,  and  this  quantity  of  steam  at 
fifty  pounds  pressure  will  do  a  certain  given  amount  of  work. 

Now,  if  you  raise  the  pressure  of  the  steam  to  one  hundred 
pounds  the  engine  will  perform  twice  as  much  work,  but  will 
not  consume  any  greater  number  of  cubic  inches  of  steam. 
And  so  it  is  with  electric  current:  One-half  of  an  ampere  at 
50  volts  will  do  a  certain  amount  of  work,  but  the  same  one- 
half  ampere  at  100  volts  will  do  just  twice  as  much.  In  other 
words,  the  amperage  or  volume  of  current  is  simply  the 
medium  through  which  the  voltage  or  pressure  (E.M.F.)  acts, 
or  works.  In  a  steam  engine,  with  the  steam  at  given  pres- 
sure, you  can  increase  the  power  of  the  engine  by  either  in- 
creasing the  size  of  the  engine  cylinder,  or  by  increasing  the 
pressure  of  the  steam.  In  a  water  motor  you  can  increase 
the  capacity  to  do  work  either  by  increasing  the  size  of  the 
motor  or  the  pressure  of  the  water.  The  same  thing  holds 


FOR    MANAGERS    AND    OPERATORS  27 

true  with  electricity.  You  can  increase  its  capacity  to  do 
work  either  by  increasing  the  volume  of  current  (amperage) 
or  by  increasing  the  voltage.  To  perform  a  given  amount  of 
work  with  a  low  pressure  (voltage)  a  large  volume  (amper- 
age) is  necessary,  but  if  the  voltage  be  high  the  same  amount 
of  work  can  be  performed  with  much  less  volume  of  current. 
In  fact,  the  number  of  horse  power  of  work  performed  by 
electric  current  is  represented  by  the  voltage  times  the  am- 
peres, divided  by  746. 

Ohm. — Water  in  passing  through  a  pipe  encounters  resist- 
ance, by  reason  of  the  rough  sides  of  the  pipe,  as  well  as  by 
reason  of  the  internal  resistance  of  the  water  itself.  This 
resistance  tends  to  retard  the  flow.  Precisely  the  same  is 
true  with  electricity.  In  passing  through  a  wire  electric  cur- 
rent encounters  resistance,  and  this  resistance  tends  to  retard 
the  flow  of  current.  It  is  measured  in  ohms,  the  definition  of 
which  is  given  elsewhere.  The  effect  of  resistance  is  to  pro- 
duce heat.  In  a  water  pipe  the  resistance  increases  as  the 
volume  of  water  passing  through  the  pipe  is  increased,  or  as 
the  pipe  is  made  smaller  in  relation  to  the  volume  of  water 
flowing.  It  decreases  as  the  pipe  is  made  larger  with  refer- 
ence to  the  volume  of  water  flowing.  The  same  thing  is  true 
of  current.  Having  a  wire  of  given  area,  the  resistance  in- 
creases as  the  current  flow  becomes  greater,  and  decreased  as 
the  current  flow  becomes  less,  or,  having  a  given  current  flow 
the  resistance  increases  as  the  diameter  of  the  wire  is  made 
less  or  its  length  is  increased,  or  decreases  as  the  diameter 
of  the  wire  is  made  greater  or  its  length  is  decreased. 

Watt. — Watt  is  the  unit  used  to  measure  the  amount  of 
electrical  energy  expended — the  amount  of  work  actually  per- 
formed. It  is  found  by  multiplying  the  voltage  by  the  am- 
perage, and  is  transformed  into  horse  power  by  dividing  by 
746,  since  746  w,atts  equal  one  horse-power. 

For  example:  If  we  have  10  amperes  flowing  at  110  volts, 
the  amount  of  energy  expended  would  be  equal  to  110  X  10  = 
1100  watts,  which,  divided  by  746=  1.47  h.  p.  If,  on  the  other 
hand,  we  had  110  amperes  flowing  at  10  volts  the  result  would 
be  the  same.  But  if  we  had  10  amperes  flowing  at  10,000  volts 
then  we  would  have  electrical  energy  expended  (work  per- 
formed) as  follows:  10,000X10=100,000  watts  -f-  746  =  134 
h.  p. 


28  MOTION    PICTURE    HANDBOOK 

Use  of  Electrical  Terms  in  Calculation 

IT  is  quite  problematical  as  to  how  much  use  the  average 
operator  will  be  able  to  make  of  electrical  terms  in  mak- 
ing calculations,  since,  in  order  to  find  an  unknown 
quantity  he  must  know  two  other  quantities.  In  order  to  cal- 
culate the  number  of  amperes  flowing  in  a  circuit  it  is  neces- 
sary the  voltage  and  resistance  in  ohms  be  accurately  known, 
and,  while  the  operator  usually  knows  about  what  the  voltage 
is,  the  resistance  is  seldom  a  known  quantity,  or  one  which 
the  operator  can  readily  ascertain  with  any  degree  of  ac- 
curacy. To  find  the  number  of  ohms  resistance,  the  operator 
must  know  the  exact  amperage  and  voltage,  which  he  can,  if 
necessary,  obtain  by  means  of  a  reliable  voltmeter  and  am- 
meter. To  find  the  voltage  he  must  know  the  exact  resistance 
in  ohms  and  the  exact  amperage.  But,  notwithstanding  the 
fact  that  only  two  of  these  quantities  are  usually  known  to 
the  operator,  and  those  two  often  only  known  approximately, 
the  operator  ought  to  understand  how  to  make  electrical  cal- 
culations, particularly  with  relation  to  his  projection  arc  cir- 
cuit, and  I  shall  therefore  give  a  somewhat  extended  explana- 
tion of  the  method. 

The  operator  must  fix  firmly  in  his  mind  the  fact  that  where 
the  projection  lamp  circuit  is  concerned  the  resistance  does 
not  lie  wholly  in  the  rheostat,  or  whatever  takes  its  place. 
The  wires,  lamp  arms  and  carbons  offer  small  resistance,  but 
a  very  considerable  portion  of  the  total  is  in  the  arc  itself. 
The  resistance  of  the  wires,  lamp  arms  and  carbons  may,  for 
ordinary  purposes,  be  neglected,  but  unless  the  resistance  of 
the  arc  itself  be  taken  into  consideration  a  very  serious  error 
will  result. 

When  making  electrical  calculations  it  is  customary,  for  the 
sake  of  brevity,  to  use  the  letters  E,  C  and  R.  E  stands  for 
"electro-motive  force,"  which  is  merely  another  name  for 
voltage,  hence  E  stands  for  voltage;  C  stands  for  current  flow, 
meaning  amperes,  hence  C  stands  for  amperes;  R  stands  for 
resistance  in  ohms,  hence  R  stands  for  ohms. 

The  operator  should  also  remember  that  in  a  common  frac- 
tion the  horizontal  line  always  means  "divided  by,"  thus  ^ 
really  means  1  4-  2.  But  I  think  I  hear  some  one  say  you 
cannot  divide  one  by  two.  Oh,  yes,  you  can.  It  is  done 
thusly:  We  put  down  the  one,  followed  by  a  period,  called  a 
"decimal  point,"  and  then  add  ciphers,  thus:  1.00.  We  now 
have  1.00  with  a  decimal  point  between  the  one  and  the  two 
OOs,  and  1.00  -4-  2  =  .50,  or,  .5,  which  is  exactly  the  same  thing 


FOR   MANAGERS    AND   OPERATORS  29 

as  50/100,  5/10,  or  1/2.  The  rule  .is  to  count  the  figures  or 
ciphers  to  the  right  of  the  decimal  point  in  the  number  being 
divided,  and  then,  beginning  at  the  last  figure  of  the  result, 
count  an  equal  number,  and  place  the  decimal  to  the  left  of 
the  last  figure  counted.  If  there  are  not  enough  figures  in  the 
result  to  do  this,  then  add  ciphers  to  the  left. 

E 
When  dealing  with  formulas,  —  means   that  the   quantity 

C 

represented  by  E  is  to  be  divided  by  the  quantity  represented 
by  C,  E  being  the  voltage  and  C  amperes.  If  there  be  two 
or  more  quantities  above  or  below  the  line,  with  no  sign  be- 
tween them,  it  means  they  are  to  be  multiplied  together,  thus: 
E 

means  that  E  (volts)  is  to  be  divided  by  C  (amperes) 

C  R 

E  — 15 

multiplied  by  R  (ohms), means  that  after  15  has  been 

C 

subtracted  from  the  quantity  represented  by  E  (volts)  it  is 
to  be  divided  by  the  quantity  represented  by  C  (amperes). 
The  student  will  be  greatly  benefited  if  he  will  practice  writ- 
ing out  formulas  of  this  kind  in  letters,  substituting  quantities 
in  figures  and  working  them  out. 

Ohms  law  sets  forth  the  fact  that  the  number  of  amperes 
flowing  are  equal  to  the  voltage  divided  by  the  resistance  in 

E 

ohms.     We,  therefore  have  —  =  C,  or,  in  other  words,  volts 

R 

divided  by  ohms  equals  amperes.  It  then  follows  that  if 
E 

—  =  C,  C  multiplied  by  R  must  equal  E.    It  also  follows  that 
R 

E 

• —  =  R.    It  works  out  as  follows:   We  know  that  the  ordinary 

C 

110-volt   16   c.p.   carbon   filament  incandescent   lamp   requires 

approximately  one-half  ampere  of  current  to  bring  it  up  to 

candle  power.     What  is   its  resistance?     Using  the   formula 

E  110  volts 

—  =  R,   substituting  figures,  we  have  —  =  220, 

C  .5  of  an  ampere 

the  number  of  ohms  resistance  in   the  filament  of  the  lamp. 


30  MOTION    PICTURE    HANDBOOK 

E  110 

Again  applying  the  formula  —  =  C,  we  have —  =  .5,  or  ^2,  as 

R  220 

the  amperage  110  volts  will  force  through  220  ohms  resistance. 
It  seems  to  me  all  this  is  simple  enough  of  understanding  and 
application,  but  to  make  it  yet  more  plain  I  will  take  the 

E 
formula  —  =  R,  which  means  voltage  divided  by  amperes  equal 

C 

ohms,  so  that  if  the  voltage  be  50  and  the  amperes  10,  E  would 
mean  50,  C  10,  and  R  would  be  50  -^  10  =  5,  but  if  the  voltage' 
be  110  and  the  amperage  5,  then  E  would  mean  110,  C  5  and 
R  would  be  110 -i- 5  =  22  ohms. 

When,  however,  we  come  to  consider  the  projection  arc 
circuit,  a  new  element  enters  in  the  shape  of  the  resistance  of 
the  arc  itself,  and  if  we  propose  to  be  absolutely  accurate  we 
must  consider  also  the  resistance  of  the  carbon  arms,  wires, 
etc.,  but  that  degree  of  refinement  is  seldom  or  never  neces- 
sary in  a  projection  circuit  calculation. 

In  leaping  the  air  gap  between  the  carbon  tips  of  the  arc 
lamp  the  current  encounters  high  resistance.  In  overcoming 
resistance  voltage  is  consumed,  as  will  be  more  thoroughly 
set  forth  and  explained  under  "Resistance,"  Page  34.  Tn  other 
words,  when  current-flow  is  opposed  by  resistance,  and  that 
resistance  is  overcome,  there  is  a  consequent  drop  in  pressure 
or  voltage;  pressure  has  been  used,  or  consumed  in  the  proc- 
ess. The  resistance  of  the  arc,  consequently,  the  voltage 
drop  in  overcoming  the  resistance,  is  proportional  to  (a) 
length  of  arc;  (b)  size  and  characters  of  the  carbons;  (c)  kind 
of  core  in  the  carbon;  (d)  number  of  amperes  flowing.  All 
these  factors  enter  very  decidedly  into  the  equation,  but  very 
largely  the  resistance  encountered  is  directly  proportional  to 
the  length  of  the  arc. 

For  reasons  not  necessary  to  enter  into  at  this  time  the 
D.  C.  arc,  for  a  given  amperage,  is  longer  than  the  A.  C.  arc. 
It,  therefore,  follows  that  its  resistance  will  be  higher.  The 
accepted  theory  is  that  all  voltage  is  consumed  at  the  arc. 
Whether  or  not  this  is  true  is  a  highly  technical  question, 
which  it  would  be  unprofitable  to  discuss  in  these  pages.  We 
shall  accept  the  theory.  Therefore  the  rheostat  or  whatever 
takes  its  place  must  cut  down  the  voltage  to  just  that  pressure 
which  the  resistance  of  the  arc  will  consume  when  burning 
normally. 

When  an  ordinary  D.  C.  projection  arc  is  operating  at  its 
best  it  consumes  about  48  volts.  The  D.  C.  arc  voltage  varies 


FOR    MANAGERS    AND    OPERATORS  31 

from  45  to  55,  but  48  is  a  fair  average.  In  other  words,  the 
current  must  reach  the  arc  at  that  pressure,  and  that  pressure 
will  be  consumed  in  the  arc.  Ordinarily  it  is  spoken  of  as 
"48  volts  drop  across  the  arc."  What  is  the  resistance  of 
such  an  arc  operating  at  40  amperes?  Knowing  the  voltage 

E 
(48),  and  amperage,  we  apply  the  formula — =  R,  and  have 

C 

48  -T-  40  =  1  1/5  ohms  arc  resistance.  Let  us  prove  this  out. 
Suppose  the  line  voltage  to  be  110.  The  total  resistance  must 

E 
equal    ( — =  R)   the  voltage  divided  by  the  amperes  flowing; 

C 

therefore,  the  amperage  being  40,  the  resistance  must  be 
110  -r-  40,  or  23/4  ohms.  We  have  seen  that  the  arc  resistance 
is  1  1/5  ohms  with  its  voltage  at  48.  Subtracting  the  arc 
voltage  from  the  line  voltage  leaves  us  62,  as  the  drop  in  vol- 
tage there  must  be  across  the  rheostat.  Again  applying  the 

E 
formula  ( —  =  R),  we  have  62  -r-  40  =  1  11/20  as  the  ohmic  re- 

C 

sistance  of  the  rheostat.  Adding  this  and  the  arc  resistance 
together,  we  have  a  total  of  (1  1/5  +  1  11/20)  23/4,  as  the  total 
resistance,  which  corresponds  to  the  total  resistance  necessary 
to  allow  40  amperes  to  pass  through. 

If  the  amperage  were  45,  then  the  total  resistance,  voltage 
remaining  the  same,  must  be  less.  If  the  amperage  were 
less,  then  the  resistance  would  necessarily  be  greater.  The 
higher  the  voltage  the  greater  must  be  the  resistance,  as  will 

E 
be  seen  by  applying  the  formula —  =  R,  to  accomplish  a  given 

C 

current  flow.  Resistance  is  always  found  by  application  of 
the  formula  last  quoted. 

Arc  resistance,  as  we  have  said,  will  vary  somewhat,  accord- 
ing to  the  character  of  carbons  and  cores,  the  amount  of  cur- 
rent flowing  and  the  arc  length,  particularly  the  latter.  How- 
ever, with  the  D.  C.  projection  arc  we  are  reasonably  safe  in 
taking  the  constant  48,  for  the  arc  drop,  or  arc  voltage,  unless 
the  amperage  is  low — say  30,  or  less,  when  45  will  serve  better. 
Such  a  standard  is  necessary,  even  though  more  or  less  in- 
accurate, since  the  operator  sel-dom  has  a  voltmeter  with 
which  to  measure  the  arc  voltage  exactly.  Instead  of  applying 


32  MOTION    PICTURE    HANDBOOK 

E 

the   formula  —  =  R,  as   it   stands,   we   first   subtract   the   arc 

C 

voltage  (using  the  standard  48),  from  E,  which  represents  the 
line  voltage,  thus  securing,  at  one  operation,  the  total  resist- 
ance other  than  that  of  the  arc.  The  problem  then  reads,  for 

E—  48 
any  D.  C.  arc  above  30  amperes,  -  '=R,  but  the  "R"  in 

C 

this  case  is  the  necessary  ohmic  resistance  except  that  peculiar 
to  the  arc  itself.  In  subtracting  48  we  have  accounted  for  the 
arc  resistance.  For  an  arc  of  30  amperes,  or  less,  the  formula 


is  -  =  R.     For  the  ordinary  A.  C.  projection  arc,  up  to  60 
C 

E—  35 
amperes,    the   formula   to   be   used    is  -  =  R.      In    other 

C 

words  we  use  35  as  the  A.  C.  constant  for  arc  voltage,  instead 
of  the  48  used  for  D.  C. 

Suppose  we  wish  to  construct,  or  order  a  rheostat  to  deliver 
25  amperes  on  125  volts  line  pressure,  when  working  in  series 

E—  45 
with  a  D.  C.  projection  arc.     We  use  the  formula  -  =  R. 

C 

125-45 
Substituting  figures  for  letters  we  have  --  ,  which  equals 

25 

the  necessary  ohmic  resistance  of  the  rheostat,  not  taking  ac- 
count of  line  and  carbon  resistance.  125  —  45  =  80  and 
80  -T-  25  =  3  1/5,  the  number  of  ohms  resistance  the  rheostat 
must  contain.  If  it  were  a  40  ampere  arc  we  would  subtract 
48  instead  of  45.  If  it  were  an  A.  C.  arc  we  would  subtract  35. 
Were  we  to  connect  the  same  rheostat  between  the  wires  of 
a  circuit  carrying  the  same  voltage  without  an  arc  in  series, 
or,  what  amounts  to  practically  almost  the  same  thing, 
freeze  the  carbons  of  the  arc  lamp,  we  would  then  find  the 
3  1/5  ohm  rheostat,  which  delivered  25  amperes  in  series  with 

E 
an   arc,  to   be   delivering    (  —  =  C)    110-=-  3.2  =  34.4   amperes, 

R 

almost. 

RULE  OF  THUMB 

There  is  a  very  simple  formula,  easy  of  application,  which 
combines  the  three  formulas  into  one.     It  is  called  the  "Rule 


FOR    MANAGERS    AND    OPERATORS  33 

E 

of  Thumb."    It  is  expressed  for  general  use  as: . 

CR 

To  use  the  formula  you  have  but  to  cover  the  symbol  or 
letter  representing  the  quantity  desired,  and  what  remains 
will  produce  the  answer,  thus:  Suppose  we  wish  to  ascertain 
the  resistance  in  ohms.  We  cover  up  the  "R"  in  the  formula 

E 
and  find   that  we   have  —  remaining,  which  will   give   R,   the 

C 

desired  quantity.  In  using  this  formula  on  projection  circuits 
the  top  letter  must  be  expressed  as  E  minus  the  arc  voltage, 
the  same  as  in  the  regular  formulas,  thus: 

E-48         E— 45  E— 35 

or for  D.  C.  and for  A.  C. 

CR  CR  CR 


Go  to  your  work  each  day 
as  though  it  ^vere  your 
first  day  on  a  new  job 
and  you  had  to  make  good. 


34  MOTION    PICTURE    HANDBOOK 


Resistance 


ONE  of  the  most  difficult  problems  confronting  the  oper- 
ator and  the  electrician  is  resistance.  This  is  a  factor 
which  is  met  with  in  almost  every  phase  of  electrical 
work,  and,  so  far  as  light  be  concerned,  it  may  be  said  to  be 
the  very  foundation  stone  of  the  structure. 

How  Resistance  Acts. — In  passing  through  a  wire,  current 
encounters  resistance,  which  is,  in  its  action,  very  similar  to 
that  encountered  by  water  under  pressure  in  passing  through 
a  pipe.  When  water  flows  through  a  pipe  it  encounters  resist- 
ance directly  in  proportion  to  the  size  and  length  of  the 
pipe  and  the  quantity  of  water  flowing  per  minute.  This 
resistance  is  to  some  extent  the  result  of  molecular  friction 
within  the  water  itself,  but  mostly  it  is  caused  by  friction  be- 
tween the  water  and  the  sides  of  the  pipe.  In  a  pipe  of  given 
diameter,  resistance  increases  with  (a)  increase  of  the  flow, 
or  volume  of  water,  (b)  increase  of  the  length  of  the  pipe, 
and  (c)  with  the  roughness  of  the  inside  of  the  pipe.  Con- 
versely it  decreases  with  decrease  of  the  flow,  the  shortening 
of  the  pipe  or  with  increased  smoothness  of  pipe  walls.  With 
a  given  flow  of  water,  resistance  increases  with  the  length 
of  the  pipe,  the  decrease  in  its  diameter  or  added  roughness, 
and  decreases  as  the  pipe  is  made  larger  or  shorter  or 
smoother. 

Resistance  consumes  pressure,  and  pressure  is  consumed 
exactly  in  proportion  to  the  amount  of  resistance  encountered. 
In  the  second  edition  of  my  Handbook  I  explained  this  propo- 
sition by  means  of  a  diagram,  and  I  do  not  think  that 
particular  thing  can  be  improved  upon,  therefore  it  is  herewith 
reproduced  in  somewhat  different  form. 

In  the  illustration  we  see  a  water  main,  with  a  pressure 
gauge  registering  100  pounds,  to  which  are  connected  three 
pipes  A,  B,  and  C.  On  A  is  a  pressure  gauge  placed  right  up 
close  to  the  main  pipe  and  another  near  its  outer  end.  We 
will  assume  the  diameter  of  this  pipe  to  be  one-half  inch.  At 
B  is  a  short  pipe  of  the  same  diameter;  at  C  is  a  pipe  three 
inches  in  diameter  for  ten  feet  of  its  length,  with  a  three-foot 
extension  of  half-inch  pipe  at  its  end.  At  the  outer  end  of 
the  large  pipe  is  a  pressure  gauge,  with  another  at  the  end 


FOR  MANAGERS  AND  OPERATORS 


35 


of  the  extension.  Now  let  us  consider  the  action.  Pipe  B  is 
short  and,  being  open  at  its  end,  the  water  spurts  out  with 
great  force,  carrying  itself  almost  horizontal  for  a  consider- 
able distance,  thus  showing  that  the  pressure  at  the  mouth  of 
the  pipe  is  high.  The  water  at  the  end  of  pipe  A  does  not 
come  out  with  such  great  force,  and  if  we  examine  gauge 
No.  1  and  gauge  No.  2  we  shall  find  that,  whereas  gauge  No.  1 
registers  very  nearly  the  same  as  the  one  on  top  of  the  main 
pipe,  No.  2  will  register  far  less.  Gauges  No.  1  and  No.  2 
are  on  the  same  pipe.  What  is  the  explanation  of  the  differ- 
ence in  pressure? 

The  answer  is  simple.  It  has  been  used  up  in  forcing  the 
water  at  high  speed  against  the  friction  of  the  pipe.  The 
pipe  is,  under  the  conditions,  working  above  its  normal  capac- 


Figure  6. 

ity,  with  the  result  that  very  high  resistance  is  developed, 
and  the  greater  the  resistance  the  more  power  (pressure)  is 
consumed  in  overcoming  it. 

Examining  gauge  No.  3  at  the  end  of  the  large  section  of 
pipe  C,  we  find  that  it  stands  almost  if  not  quite  at  equal  pres- 
sure with  the  one  on  top  of  the  main,  although  it  is  ten  feet 
from  the  main,  whereas  gauge  No.  4,  at  the  end  of  the  small 
three-foot  section,  shows  considerably  less.  What  is  the  rea- 
son for  this? 

Again  the  answer  is  simple.  The  volume  of  water  passing 
through  the  short'  pipe  is  very  great  as  compared  with  its 
diameter.  It  is  rushing  through  at  high  speed,  therefore  the 
friction  or  resistance  encountered  is  high,  with  the  result 
that  pressure  is  used  up  very  rapidly  in  forming  the  water 
against  it.  On  the  other  hand,  while  precisely  the  same 


36  MOTION    PICTURE   HANDBOOK 

volume  or  amount  of  water  is  passing  through  the  large  sec- 
tion of  the  pipe  it  is  moving  quite  slowly,  hence  the  resistance 
it  encounters  is  comparatively  slight,  and  very  little  power 
is  necessary  to  overcome  it. 

The  pressure  at  which  the  water  might  be  would  not  affect 
the  result,  except  that  if  it  be  very  low  not  much  resistance 
could  be  overcome.  A  pipe  of  given  diameter  will  carry  water 
up  to  its  capacity  (the  capacity  of  a  pipe  may  be  said  to  have 
been  reached  zvhen  its  resistance  to  the  flow  of  water  becomes 
excessive,  so  that  there  is  a  considerable  waste  of  power  in  forc- 
ing the  water  through}  under  any  pressure  sufficient  4:o  move  the 
liquid  and  less  than  that  sufficient  to  burst  the  pipe.  A  pipe  of 
given  diameter  will  convey  only  a  certain  number  of  gallons  of 
water  per  minute  without  excessive  friction,  regardless  of  whether 
the  pressure  be  10  or  100  pounds  per  square  inch,  but  when  the 
point  is  reached  where  resistance  to  flow  becomes  excessive,  the 
normal  capacity  of  the  pipe  is  said  to  have  been  reached.  True, 
we  can  still  force  a  great  deal  more  water  through,  but  it  will 
be  at  the  expense  of  largely  increased  power  consumption.  It 
costs  money  to  force  a  water  pipe  above  its  capacity,  and  the 
cost  increases  very  rapidly  in  proportion  to  the  excess  of 
capacity;  in  other  words,  the  higher  the  excess  over  capacity 
the  greater  the  relative  cost  of  overcoming  the  resistance. 

The  practical  method  of  reducing  this  resistance  is  to  in- 
crease the  diameter  of  the  pipe  until  the  desired  flow  is  had 
with  only  a  normal  friction  loss.  We  therefore  deduce  the 
rule  that: 

Increasing  the  diameter  decreases  the  friction,  or  resistance 
offered  to  a  given  flow,  since  the  water  is  thus  caused  to  move 
more  slowly. 

But  another  equation  enters  'here,  viz.,  the  length  of  the 
pipe.  Inasmuch  as  friction  very  largely  results  from  the 
rough  side  of  a  pipe,  it  naturally  follows  that  the  longer  the 
pipe  the  more  friction  there  will  be.  We  have  already  seen 
that  with  a  given  flow  as  the  diameter  of  the  pipe  is  decreased 
(made  less),  the  friction  or  resistance  is  increased  (made 
greater),  and  conversely,  as  the  diameter  of  the  pipe  is  in- 
creased (made  greater)  the  friction  or  resistance  is  decreased 
(made  less). 

We  may  also  readily  see  that,  with  a  given  flow: 

As  the  length  of  the  pipe  is  increased  the-friction  (resistance} 
is  increased,  and,  conversely,  as  the  length  is  decreased  the  re- 
sistance is  also  made  less. 

Therefore,  we  may  increase  the  resistance  by  (a)  increas- 
ing the  flow  of  water;  (b)  decreasing  the  diameter  of  the  pipe; 


FOR    MANAGERS    AND    OPERATORS  37 

(c)  increasing  the  length  of  the  pipe;  (d)  increasing  its 
roughness. 

We  may  decrease  the  resistance  by  (a)  decreasing  the  flow; 
(b)  increasing  the  diameter  of  the  pipe;  (c)  making  the  pipe 
shorter;  (d)  making  the  pipe  smoother. 

All  this  is  simple,  and  is  or  ought  to.be  readily  understand- 
able. And  now  what  has  been  said  of  the  water  pipe  is  also  true 
with  relation  to  current  and  wires.  If  you  substitute  circuits  of 
wire  for  the  water  main  and  for  pipes  A,  B,  and  C,  with  volt- 
meters in  place  of  the  pressure  gauges,  and  lamps  or  motors 
instead  of  the  open  pipe-end  you  will  get  precisely  the  same 
relative  result  in  loss  of  pressure  (voltage)  when  current  flow  is 
sent  through  the  circuits. 

The  voltage  of  the  current  has  absolutely  nothing  whatever 
to  do  with  the  necessary  size  of  wire.  You  could  convey 
current  at  10,000  volts,  or  50,000  volts  for  that  matter,  on  a  No. 
40  wire,  which  is  no  larger  than  a  very  fine  silk  thread,  but 
on  that  wire  you  could  convey  a  very  small  quantity — amper- 
age. 

Electric  current  in  passing  through  wires'  encounters  re- 
sistance precisely  the  same  as  does  water  in  passing  through 
a  pipe.  A  wire  of  given  diameter  will  convey  a  certain  given 
number  of  .amperes  of  current  without  excessive  friction 
(resistance),  just  the  same  as  a  water  pipe  of  given  diameter 
will  convey  a  certain  given  number  of  gallons  of  water  with- 
out undue  friction  or  resistance,  and  the  point  where  resist- 
ance begins  to  rise  above  normal  marks  the  "capacity"  of  the 
wire,  just  as  it  does  the  water  pipe.  Beyond  that  point  the 
friction  or  resistance  becomes  excessive,  and  manifests  itself 
in  a  loss  of  pressure  or  voltage.  This  loss  in  pressure  has 
been  consumed  in  forcing  the  current  against  resistance,  pre- 
cisely as  was  the  case  in  the  water  pipe.  It  therefore  follows 
that  loading  wires  beyond  their  normal  capacity  is  expensive,  and 
should  be  avoided  for  that  if  for  no  other  reason,  since  the  waste 
is  registered  on  your  meter  and  you  will  have  to  pay  for  it,  ex- 
actly the  same  as  you  pay  for  current  used  in  your  lamps  or 
motors. 

But  this  is  not  all,  for  if  you  attempt  to  force  amperage  in 
excess  of  the  rated  capacity,  as  shown  by  the  Underwriters'  table 
(see  page  42),  heat  will  be  developed,  and,  if  the  matter  be  car- 
ried too  far  (which  can  only  be  done  by  overf using),  the  wires 
may  get  red,  or  even  white  hot,  finally  burning  in  two  entirely 
and  stopping  all  current  flow  and  perhaps  setting  fire  to  the 
building  in  the  process. 


38  MOTION    PICTURE    HANDBOOK 

Exactly  as  was  the  case  with  the  water  pipe,  with  a  given 
current  flow  the  resistance  of  a  wire  is  decreased  as  the  diameter 
of  the  wire  is  increased,  or  its  length  made  shorter,  and  is  in- 
creased as  the  diameter  of  the  wire  is  made  smaller  or  its  length 
decreased. 

Resistance  increases With  increased  length  of  wire;  or 

As  diameter  is  decreased;  or 

As  the  temperature  is  increased  above 

normal;  or 
As   the   composition   of   the   wire   is 

changed  to  an  alloy  having  lower 

conductivity. 

Resistance  decreases As  length  of  wire  is  decreased;  or 

As  the  diameter  is  increased. 

As  the  temperature  is  reduced,  if  it  be 

above  normal. 

As  the  composition  of  the  wire  is 
changed  to  an  alloy  having  higher 
conductivity. 

NOTE. — The  difference  in  conductivity  of  different  metals  makes  the 
analogy  of  water  and  current  action  more  complete,  since  it  corre- 
sponds to  roughness  or  smoothness  of  walls  of  the  water  pipe. 

Different  metals  offer  varying  resistance  to  electric  current  as 
follows,  taking  the  resistance  of  pure  silver  and  pure  copper  as  1. 

Copper    1         *18%  German  Silver 19 

Silver 1  Manganin 24 

Aluminum    1.5      *30%  German  Silver 28 

Platinum   6        *Advance  Wire   28 

Norway  Iron 7         *Climax  Wire 50 

Soft  Steel 8         *Nichrome   60 

*Ferro  Nickel 17 

NOTE. — The     Driver-Harris     Company,     manufacturers  of     resistance 

wires,    are    authority    for    these    figures.      I    know    of    no  more    reliable 

source   for    information   of   this  kind.      Star    (*)    indicates  Driver-Harris 
products. 

In  the  foregoing  table  the  figures  refer  to  the  amount  of 
resistance  each  metal  has,  as  compared  to  that  of  pure,  an- 
nealed copper.  For  instance,  platinum  has  6  and  climax  wire 
50  times  the  resistance  of  pure,  annealed  copper. 

I  have  selected  for  a  part  of  this  table  metals  and  composi- 
tions in  very  general  use  for  resistance  purposes.  It  will,  of 
course,  be  understood  that  the  figures  given  in  the  tables  are 
based  on  metals  and  alloys  of  a  certain  standard  purity,  but 
inasmuch  as  the  degree  of  purity  will,  in  the  very  nature  of 


FOR   MANAGERS   AND   OPERATORS  39 

things,  vary  to  some  extent,  the  figures  cannot  be  relied  upon 
for  absolute  accuracy. 

It  must  also  be  understood  that  the  resistance  of  nearly  all 
metals  increases  with  rise  of  temperature,  whereas  the  resist- 
ance of  carbon  decreases  as  its  temperature  increases.  The 
resistance  of  the  carbon  filament  of  the  incandescent  lamp  of 
the  ordinary  type  is  about  twice  as  much  when  cold  as  when 
burning  at  candle  power.  As  a  general  proposition  the  re- 
sistance of  liquids  and  insulating  materials  become  less  with 
increased  temperature. 

TEMPERATURE  COEFFICIENT— HOW  TO  USE 

The  resistance  of  a  wire  is  not  constant  at  all  temperatures. 
If  you  increase  the  temperature  of  a  metallic  wire  you  also 
increase  its  resistance,  and  this  increase  in  resistance  follows 
a  definite  law,  viz.: 

In  metals  increase  or  decrease  in  resistance  is  directly  in  pro- 
portion to  increase  or  decrease  in  temperature. 

The  factor  that  will  enable  you  to  calculate  this  increase  or 
decrease,  provided  you  know  the  difference  in  temperature, 
is  called  the  "temperature  coefficient."  In  all  catalogs  of  re- 
sistance wire  the  resistance  per  foot  of  the  material  is  given 
at  a  certain  standard  temperature,  usually  75  degrees  F,  and 
the  resistance  at  this  standard  temperature  will  form  the 
basis  for  calculation  of  increased  or  decreased  resistance  by 
reason  of  temperature  change.  The  figure  given  for  tem- 
perature coefficient  is  the  fraction  of  an  ohm  change  in  re- 
sistance for  each  degree  F  change  in  temperature,  and  this 
coefficient  must  be  multiplied  by  the  number  of  degrees  of 
the  temperature  change  from  the  standard  75  degrees,  and 
the  result  added  to  or  subtracted  from  the  standard  resistance, 
depending  upon  whether  the  material  increases  in  resistance 
with  heat  as  metal  does,  or  decreasing  with  heat  as  some 
other  substances,  carbon,  for  instance,  do.  For  example,  let 
us  assume  the  temperature  coefficient  of  a  given  material  to 
be  .001  per  degree  F.,  and  that  its  resistance  at  75  degrees  F. 
is  10  ohms.  What  will  be  its  resistance  at  175  degrees.? 

Subtracting  75  from  175  we  find  the  difference  in  tempera- 
ture to  be  100  degrees.  If  the  resistance  increases  .001  of 
an  ohm  for  each  degree  of  increased  temperature  then  for 
100  degrees  increase  of  temperature  the  increase  of  resistance 
would  be  .001X100  =  .!.  Now,  multiply  the  resistance  (10 
ohms)  at  75  degrees  by  the  fractional  increase,  which  is  .1, 


40  MOTION    PICTURE    HANDBOOK 

which  gives  us  the  actual  total  increase  of  10  X  .1  =  1  ohm,  so 
that  the  resistance  at  175  degrees  F  will  be  10  ohms,  the 
standard  resistance,  plus  1  ohm  increase,  or  a  total  of  11  ohms. 

PROPERTIES  OF  CONDUCTORS 

Electric  conductors  are  ordinarily  selected  with  one  of  two 
ends  in  view.  In  one  case  low  resistance,  tensile  strength, 
ductility,  and  cost  are  the  ruling  factors;  in  the  other  case 
comparatively  high  and  steady  resistance  is  the  important 
item. 

In  the  first  instance  conductors  for  current  distribution  is 
the  thing  considered,  and,  by  reason  of  the  fact  that  it  more 
nearly  combines  the  four  above-named  important  factors  than 
any  other  metal,  copper  has  been  selected  as  the  standard 
electrical  conductor,  an  office  which  it  shares  only,  to  some 
slight  extent,  with  aluminum,  the  latter  being  used  in  a  few 
instances  for  high  tension  lines. 

In  the  second  instance  a  material  to  offer  resistance  is  the 
thing  desired,  and  for  a  long  time  the  metal  used  almost  ex- 
clusively for  this  purpose  was  German  silver.  Gradually, 
however,  German  silver  has  been  largely  displaced,  until  it  is 
now  but  little  used  except  in  alloy  combinations  with  other 
metals. 

The  materials  now  most  generally  used  for  resistance  in 
motion  picture  projector  circuits  are  either  cast  iron,  made 
up  in  grid  form,  or  some  one  of  the  nickel-steel  resistance 
wires.  Reliable  data  concerning  the  properties  of  cast  iron  is 
difficult,  in  fact  practically  impossible  to  obtain,  but  it  may  be 
said  that  it  forms  an  excellent  and  cheap  resistance  medium 
where  considerable  variation  at  different  temperature  is  not 
of  great  importance. 

Properties  of  Resistance  Metals.— "Normal"  is  75°  F.  or  24° 
C.  The  resistance  per  mill-foot  of  pure  nickel  is  64.3  ohms 
at  normal.  Climax  resistance  wire,  made  by  the  Driver- 
Harris  Company,  Harrison,  N.  J.,  has  a  resistance  per  mill- 
foot  of  525  ohms  at  normal;  its  temperature  coefficient  is  .0004 
per  degree  F.  It  is  a  nickel  steel  alloy  with  a  resistance  fifty 
times  that  of  copper.  This  metal  is  excellent  for  rheostat 
coils. 

German  silver  is  a  composition  containing  18  per  cent,  of 
nickel.  It  is  known  as  "18  per  cent.  German  silver."  Its  re- 
sistance varies  somewhat  with  different  lots.  Its  mill-foot 
resistance  is  218  ohms  at  normal;  its  temperature  coefficient 
.00017  per  degree  F. 


FOR   MANAGERS    AND    OPERATORS  41 

Ferro  nickel  has  a  mill-foot  resistance  of  170  ohms  at 
normal;  temperature  coefficient  is  .00115  per  degree  F. 

Yankee  silver  is  a  new  alloy,  put  out  by  the  Driver-Harris 
firm,  which  is  claimed  to  be  an  improvement  on  the  18  per 
cent.  German  silver  in  that  it  withstands  rapid  heating  and 
cooling  well,  and  gives  good  service  where  German  silver 
fails.  Its  resistance  is  200  ohms  per  mill-foot;  its  tempera- 
ture coefficient  is  very  low,  being  .000086  per  degree  F. 

Nichrome,  also  a  Driver-Harris  product,  is  a  practically 
non-corrosive  alloy  with  high  melting  point — about  2600  de- 
grees F.  It  is  designed  for  use  where  high  temperatures  are 
the  rule,  such  as  heating  coils,  etc.  Its  mill-foot  resistance 
is  600  ohms;  its  temperature  coefficient  .00024  per  degree  F. 

Advance  wire,  a  Driver-Harris  product,  is  a  copper-nickel 
alloy  containing  no  zinc.  It  is  claimed  to  be  constant  in  its 
resistance  under  all  conditions  of  service;  therefore  it  has  no 
temperature  coefficient.  Resistance  per  mill-foot  is  294  ohms. 
It  is  particularly  recommended  for  electrical  instruments 
where  the  resistance  is  subjected  to  repeated  heating  and 
cooling. 

LOSS  THROUGH  RESISTANCE 

It  is  highly  desirable  and  under  certain  conditions  very 
necessary  that  the  operator  be  able  to  figure  the  resistance 
of  the  various  circuits  in  the  theatre  or  of  the  feed-wires  lead- 
ing thereto.  As  has  already  been  pointed  out,  the  overcoming 
of  resistance  consumes  voltage.  All  wires  offer  resistance 
to  current,  and  voltage  will  be  consumed  in  (a)  proportion  to 
the  size  of  the  wire;  (b)  the  length  of  the  wire;  (c)  the 
amount  of  current  flowing;  (d)  composition  of  the  wire. 

Up  to  a  certain  point  the  resistance  of  the  wire  remains 
without  change;  that  is  to  say,  the  resistance  offered  to  one 
ampere  or  ten  amperes  will  be  identical,  but  when  the  load 
becomes  such  that  the  temperature  of  the  wire  begins  to  rise, 
then  the  resistance  also  begins  to  rise,  and  the  effect  is,  as 
has  already,  been  explained,  a  loss  in  voltage,  with  the  result 
that  the  lamps  will  not  burn  to  candle  power  and  the  meter 
is  registering  wattage  which  is  being  wasted  in  overcoming 
the  excessive  resistance  of  the  wires. 

Copper  wire  used  for  electric  current  can  carry  a  certain 
number  of  amperes  without  causing  any  appreciable  rise  in 
temperature,  and  the  National  Board  of  Fire  Underwriters, 
which  is  the  controlling  factor,  has  adopted  the  amperage 
rating  recommended  by  the  American  Institute  of  Electrical 
Engineers.  This  determines  the  number  of  amperes  which 


42  MOTION    PICTURE   HANDBOOK 

any  wire  may  be  allowed  to  carry,  which  are  set  forth  in 
Table  No.  1,  in  which  "B.  &  S."  means  "Brown  &  Sharpe 
Wire  Gauge."  For  reasons  why  more  current  is  allowed  on 
weather-proof  than  on  rubber-covered  see  "Insulation,"  page  50. 

TABLE  NO.  1.    WIRE  CAPACITIES. 

Rubber  Other 

Insulation  Insulations  Circular 

B.  &  S.  Amperes  Amperes  Mills 

18  3  5  1,624 

16  6  10  2,583 

14  15  20  4,107 

12  20  25  6,530 

10  25  30  10,380 

8  35  50  16,510 

6  50  70  26,250 

5  55  80  33,088 

4  70  90  41,740 

3  80  100  52,630 

2  90  125  66,370 

1  100  150  83,690 

0  125  200  105,500 

00  IsO  225  133,100 

000  175  275  167,800 

0000  225  325  211,600 

For  insulated  aluminum  allow  84  per  cent,  of  above  table 

ratings.    The  Board  of  Fire  Underwriters  does  not  recognize 

anything  of  less  size  than  No.  18  wire,  and  nothing  less  than 

No.  14  can  be  used  for  interior  circuit  wires. 

The  figuring  of  the  resistance  of  a  wire  of  any  size  or 
length  is  a  simple  matter,  provided  the  standard  of  resistance 
for  that  particular  material  be  known. 

MILL-FOOT   STANDARD    OF   RESISTANCE 

The  accepted  standard  of  resistance  is  the  resistance  of  a 
wire  one  circular  mill  in  cross-section  (one  one-thousandth  of 
an  inch  in  diameter)  and  one  foot  in  length,  made  of  the 
same  material  as  the  wire  it  is  proposed  to  measure.  This  is 
what  is  known  as  the  "Mill-foot  standard  of  resistance."  The 
resistance  of  such  a  wire,  when  made  of  ordinary  commercial 
copper,  is  given  by  standard  text  books  as  10.5  ohms.  That 
is  to  say,  a  wire  one  foot  in  length  and  one  one-thousandth 
of  an  inch  in  diameter  (one  mill  cross-section),  made  of 
ordinary  commercial  copper,  at  normal  temperature  (75°  F.  or 
24°  C),  will  have  a  resistance  of  10.5  ohms. 


FOR   MANAGERS    AND    OPERATORS 


43 


TABLE  NO.  2 
RESISTANCE  OF  COPPER  WIRE 


So 

Resistance  at  75°  F.,  International  Units 

Sri 

R. 

Ohms 

Feet 

6  . 

Ohms 

per 

per 

Ohms  per  Lb. 

per 

Mile 

Ohm 

1000  Feet 

000000 

0.03122 

0.1649 

32036. 

0.00003070 

00000 

0.03937 

0.2079 

25398. 

0.00004881 

0000 

0.04964 

0.2621 

20147. 

0.00007758 

000 

0.06261 

0.3306 

15972. 

0.0001234 

00 

0.07894 

0.4168 

12668. 

0.0001962 

6 

0.09945 

0.5251 

10055. 

0.0003114 

1 

0.1255 

0.6627 

7968. 

0.0004960 

2 

0.1583 

0.8360 

6316. 

0.0007894 

3 

0.1966 

1.054 

5010. 

0.001254 

4 

0.2516 

1.329 

3974. 

0.001994 

5 

0.3174 

1.676 

3150. 

0.003173 

6 

0.4002 

2.113 

2499. 

0.005043 

7 

0.5044 

2.663 

1982. 

0.008013 

8 

0.6361 

3.358 

1572. 

0.01274 

9 

0.8026 

4.238 

1246. 

0.02029 

10 

1.011 

*    5.340 

988.8 

0.03220 

11 

1.277 

6.743 

783.1 

0.05135 

12 

1.609 

8.496 

621.5 

0.08154 

13 

2.026 

10.70 

493.6 

0.1293 

14 

2.556 

13.50 

391.2 

0.2058 

15 

3.221 

17.01 

310.4 

0.3268 

16 

4.070 

21.49 

245.7 

0.5216 

17 

5.118 

27.02 

195.4 

0.8249 

18 

6.466 

34.14 

154.6 

1.317 

19 

8.151 

43.04 

122.7 

2.092 

20 

10.26 

54.15 

97.51 

3.312 

21 

12.93 

68.26 

77.35 

5.263 

22 

16.41 

86.62 

60.95 

8.476 

23 

20.56 

108.6 

48.63 

13.32 

24 

26.00 

137.3 

38.47 

21.28 

25 

32.78 

173.1 

30.51 

33.84 

26 

41.54 

219.4 

24.07 

54.35 

27 

52.09 

275.0 

19.20 

85.44 

28 

66.17 

349.4 

15.11 

137.9 

29 

82.27 

434.4 

12.15 

213.1 

30 

105.1 

554.7 

9.519 

347.6 

31 

131.7 

695.4 

7.592 

546.3 

32 

166.2 

877.4 

6.018 

869.6 

33 

209.5 

1106. 

4.772 

1383. 

34 

264.6 

1397. 

3.779 

2205. 

35 

333.7 

1762. 

2.996 

3507. 

36 

420.1 

2218. 

2.380 

5558. 

37 

530.4 

2801. 

1.885 

8860. 

38 

669.9 

3537. 

1.493 

14131. 

39 

843.0 

4451. 

1.186 

22378. 

40 

1065. 

5625. 

0.9387 

35734. 

44  MOTION    PICTURE    HANDBOOK 

FIGURING  RESISTANCE  OF  CIRCUITS 

And  now  let  us  proceed  to  apply  the  foot-mill  standard  in 
measuring  wires.  Suppose  you  have  a  wire  400  feet  in  length 
and  1  mill-foot  in  cross-section  (1/1000  of  an  inch  in  diameter) 
made  of  ordinary  commercial  copper.  It  is  evident  that  if 
one  foot  of  such  a  wire  has  a  resistance  of  10.5  ohms,  400 
feet  would  have  a  resistance  four  hundred  times  as  great,  or 
10.5X400  =  4200  ohms.  The  resistance  of  a  wire  of  given 
length,  however,  decreases,  as  its  diameter,  area  or  cross-sec- 
tion is  increased.  Now  if  our  400-foot  wire  has  a  diameter 
of  250  mills  it  will  have  a  cross-section  equal  to  250  X  250  = 
62,500  C.  M.,  and  it  follows  that  its  resistance  would  be  equal 
to  the  resistance  of  400  feet  of  one-mill  wire  (4,200  ohms) 
divided  by  the  C.  M.,  cross-section  of  the  larger  wire  (62,500), 
since  it  would  be,  in  effect,  equal  to  62,500  wires,  each  one 
circular  mill  in  cross-section,  or  one  mill  in  diameter.  From 
this  we  get  the  rule: 

To  find  the  resistance  of  a  copper  wire,  multiply  its  length  in 
feet  by  10.5  and  divide  that  product  by  its  area  in  circular  mills. 

In  measuring  circuits,  however,  it  is  customary  to  take  the  one 
way  length  and  double  the  mill-foot  standard,  thus:  multiply  the 
one  way  length  of  the  circuit  by  21  (10.5X2  =  21)  and  divide 
that  product  by  the  area  of  the  wire  in  the  circuit;  expressed 
in  circular  mills. 

For  example:  What  is  the  resistance  of  a  two-wire  oper- 
ating room  feed  circuit  300  feet  in  length — size  of  the  wire 
No.  5?  Now  if  we  were  just  measuring  one  300-foot-long  wire 
we  would  apply  the  above  rule,  using  10.5  as  the  standard  of 
resistance,  but  as  a  matter  of  fact  a  circuit  300  feet  long  has 
600  feet  of  wire,  and,  for  convenience  sake,  we  double  the 
mill-foot  standard,  instead  of  doubling  the  wire  length. 

In  Table  1,  page  42,  we  find  that  No.  5  wire  has  a  cross- 
section  of  33,088  C.  M.    We  then  .have  the  problem: 
Length  of  circuit  X  21       300  X  21 

= =  1874,  or  say  .2  of  an  ohm, 

Area  of  wire  33,088 

which  is  the  resistance  of  the  circuit.  This  rule  is,  of  course, 
based  on  the  proposition  that  the  wire  will  not  exceed  75 
degrees  F.,  or  24  degrees  C.  However,  the  rise  and  fall  in 
temperature  caused  by  ordinary  climatic  conditions  is  not 
sufficient  to  effect  the  result  materially.  In  fact,  resistance 
does  not  begin  to  rise  appreciably  until  the  temperature  has 
increased  sufficiently  to  be  sensible  to  the  feeling;  beyond 
that  point  it  increases  very  rapidly  with  the  temperature. 


FOR   MANAGERS    AND    OPERATORS  45 

The  foregoing  is  good  for  any  number  of  amperes  up  to  the 
capacity  of  the  wire,  or,  in  other  words,  until  the  load  becomes 
great  enough  to  cause  a  distinct  rise  in  temperature.  For 
instance:  If  you  propose  to  carry  only  5  amperes  on  a  No.  5 
wire  you  would  have  exactly  the  same  total  resistance  you 
would  have  if  you  pulled  50. 

Theoretically  this  is  not  strictly  true,  since  there  is  a  rise 
in  temperature  with  any  increase  in  current,  but  it  is  true  in  prac- 
tice, nevertheless,  by  reason  of -the  fact  that  with  any  load 
less  than  the  wire's  capacity  the  temperature  rise  is  too  slight 
to  have  appreciable  effect. 

When  figuring  copper  wire  resistance  still  another  equation 
enters,  however,  and  a  very  important  one,  too,  viz.,  drop  in 
voltage. 


FIGURING  VOLTAGE  DROP 

It  has  been  laid  down  as  a  general  rule  that: 

For  the  transmission  of  any  given  amperage  the  most  econom- 
ical condition  is  one  where  the  line  resistance  is  of  such  value  that 
the  value  of  the  energy  wasted  in  heat  in  overcoming  the  resist- 
ance of  the  line  will  be  equal  to  the  interest  per  annum  on  the 
original  cost  of  the  conductor. 

The  question  of  drop  in  voltage  in  theatre  circuits  is  usually 
given  too  little  consideration.  Where  the  length  of  the  cir- 
cuit, the  cross-section,  or  area  of  the  wire,  together  with  its 
mill-foot  standard  of  resistance,  is  known,  the  ohmic  resist- 
ance may  be  calculated  according  to: 

21  XL 

Formula  No.  1:   R  = 

A 

in  which  R  is  resistance  in  ohms;  L  the  one-way  length  of  the 
circuit,  expressed  in  feet;  A  the  cross-section,  or  area  of  the 
wire  in  circular  mills,  and  21  a  constant  equal  to  twice  the  re- 
sistance of  the  mill-foot  standard  for  copper  wire.  Twenty- 
one  and  the  one-way  length  of  the  circuit  are  used,  instead  of 
10.5  and  the  total  length  of  the  two  wires,  merely  for  the 
sake  of  convenience. 

Formula  No  2:     e  =  IXR 

in  which  e  is  the  voltage  drop;  I  the  current  in  amperes,  and 
R  the  resistance  of  the  circuit. 

21  X  I  X  L 

Formula  No.  3:     e  = in  volts. 


46  MOTION    PICTURE    HANDBOOK 

21  X  I  X  L 
Formula  No.  4:     A  = in  circular  mills. 


Formula  No.  5:     1  = in  amperes 


Formula  No.  6:     L  = in  feet. 

21X1 

When  it  is  required  to  give  a  working  formula  for  a  given 
number  of  lamps  expressed  by  N,  each  of  which  requires  am- 
peres represented  by  I,  use  Formula  No.  7. 

21  X  N  X  I  X  L 
Formula  No.  7:     A  = area  in  circular  mills. 


When  the  drop  is  expressed  as  a  percentage,  the  size  of  the 
wire  may  be  determined  by  Formula  No.  8. 

2100  X  I  XL 
Formula  No.  8:     A  = area  in  circular  mills,  E 

EXP 

being  the  voltage  of  the  circuit  and  P  the  percentage  drop. 

Where,  as  is  often  the  case,  the  power,  W,  is  given  in  watts 
instead  of  amperes,  use  Formula  No.  9. 

2100  X  WXL 
Formula  No.  9:     A  = area  in  circular  mills. 

PXE 

If  it  is  desired  to  find  the  number  of  lamps  to  which  a  given 
size  of  wire  will  supply  current  with  a  given  drop  use  For- 
mula No.  10. 

AXe 

Formula  No.  10:     N  = 

21  X  L  X  I 

Applying  formula  No.  2,  let  us  assume  a  current  of  100 
amperes  in  a  circuit  whose  resistance  figures  .02  of  an  ohm. 
Multiplying  100  amperes  by  .02  we  get  2  volts  as  the  drop  in 
that  circuit.  Formulas  Nos.  3,  4,  5,  6,  7,  8,  9,  and  10  are  ob- 
tained by  substituting  the  value  of  R  in  Formula  No.  2  for  R 
in  Formula  No.  1.  Also  for  convenience  L  (length  of  circuit) 


FOR   MANAGERS    AND   OPERATORS  47 

is  made  equal  to  2L,  so  that  only  the  distance  one  way  need 
be  considered. 

And  now  let  us  assume  an  example.  A  two-wire  operating 
room  feeder  supplies  50  amperes  at  a  distance  of  200  feet  from 
the  house  switchboard;  the  drop  allowed  is  5  per  cent,  the 
voltage  110.  What  size  wire  should  be  used?  Referring  to 
the  formula,  we  select  No.  8,  and,  substituting  figures,  the 
necessary  size  of  wire  is  found  as  follows: 

2100  X  50  X  200 

A  = —  38181  circular  mills. 

110  X. 05 

Turning  to  our  capacity  table  we  find  that  a  No.  4  wire  has 
an  area  of  41738  CM.  and  a  No.  3  has  52624,  so  that  a  No.  3 
would  be  largely  in  excess  of  the  requirements  and  a  No.  4 
would  be  too  small. 

If  this  energy  were  used  for  ten  hours  a  day  for  300  days 
and  the  cost  of  the  energy  were  8  cents  per  k.w.  hours,  the 
total  yearly  cost  would  be: 

50  X  HO  X  300  X  .08 

==  $1,320 

1000 

five  per  cent,  of  which  is  $66,  which  latter  amount  would  ex- 
press a  yearly  loss  due  to  the  5  per  cent,  drop  when  using  50 
amperes  at  110  volts.  The  cost  of  400  feet  of  No.  4  wire  would 
be  about  $21,  hence  the  yearly  loss  would  be  more  than  three 
times  the  cost  of  the  wire,  and,  without  further  calculation, 
it  is  very  readily  seen  that  No.  4  wire  would  not  be  econom- 
ical for  this  service.  If,  on  the  other  hand,  wires  sufficiently 
large  to  only  cause  a  four  per  cent,  loss  be  used,  it  is  no 
difficult  matter  to  figure  out  the  saving  and  discover  the 
fact  that  it  would  considerably  more  than  pay  interest  on 
the  added  copper  cost  with  current  at  8  cents  per  kilo- 
watt. Suppose,  however,  the  price  of  electricity  were  6  cents 
per  k.w.  instead  of  8.  The  installation  of  such  a  large  cable 
would  then  not  be  profitable,  since  the  saving  would  be  less, 
hence,  less  investment  in  copper  would  be  necessary. 

This  data  is  of  much  importance  to  both  operator  and  man- 
ager, because  by  the  use  of  the  B.  &  S.  wire  gauge  and  a  tape 
line  they  will  be  able  to  figure  out  the  approximate  loss  in 
their  various  circuits,  and  in  many  instances  it  will  be  found 
that  they  are  paying  heavily  for  energy  wasted  in  line  resist- 
ance. There  .are  many  operating  room  feed  circuits  that  are 
giving  a  5  per  cent,  drop,  or  even  larger  than  that,  and  all  this 


48  MOTION    PICTURE   HANDBOOK 

waste  energy  is  registered  on  the  wattmeter.  Therefore,  I 
repeat,  it  is  essential  that  the  operator  and  manager  have  a 
good  working  knowledge  of  questions  of  this  kind. 

Note:  In  the  foregoing  I  neglected  to  include  increase  of 
cost  for  installing  larger  wires.  This  must  be  added  to  initial 
cost  of  wire  in  order  to  arrive  at  the  correct  result. 

Further  data  on  resistance  as  applied  to  the  projection  lamp 
arc  circuit  will  be  found  under  the  head,  "Resistance  Devices." 


Measuring  Wires 

LECTRIC  conductors  of  various  kinds  are  measured  as 
to  their  cross-section  or  area  in  square  and  circular 
mills,  circular  mills  being  used  for  round  wires  and 
square  mills  for  square  or  rectangular  conductors. 

A  square  measuring  1/1000  of  an  inch  on  each  of  its  four  sides 
is  called  a  "square  mill.'*  A  circle  1/1000  of  an  inch  in  diameter 
is  called  a  "circular  mill,"  commonly  designated  "CM." 

A  round  wire  1/1000  of  an  inch  in  diameter  is  said  to  have 
an  area  of  cross-section  of  one  circular  mill. 

The  areas  of  all  round  wires  are  directly  proportioned  to  the 
square  of  their  diameters,  the  calculation  being  made  in  mills 
(thousandths  of  an  inch). 

"Squaring  the  diameter"  means  multiplying  the  diameter  by 
itself. 

It  therefore  follows,  if  the  areas  of  the  circles  are  propor- 
tional to  the  squares  of  their  diameters,  and  the  area  of  a  wire 
one  mill  in  diameter  is  called  one  mill,  or  one  "circular  mill" 
(C.M.),  then  wires  of  other  sizes  have  an  area  of  cross- 
section,  numerically  equal,  in  circular  mills,  to  their  diameter 
in  one  one-thousandths  of  an  inch  (mills)  squared,  or  multi- 
plied by  itself,  thus:  If  a  wire  be  10  mills  in  diameter,  then 
100  (10  X  10)  is  the  "square"  of  its  diameter,  hence  its  area  of 
cross-section  in  CM. 

Let  us  also  consider  a  wire  one-quarter  of  an  inch  in  diam- 
eter. Since  the  wire  is  one-quarter  inch  in  diameter,  and  one 
inch  is  equal  to  1000/1000,  then  the  diameter  of  the  wire  ex- 
pressed in  thousandths  of  an  inch,  or  mills,  would  be  equal 
to  1000-^4  =  250.  Such  a  wire  would  then  be  250/1000  of  an 
inch  in  diameter,  or,  expressed  otherwise,  250  mills  in  diam- 
eter. And  since  the  area  of  cross-section  of  a  wire  in  circular 
mills  is  equal  to  its  diameter  in  mills  multiplied  by  itself 
(squared),  it  follows  that  the  area  of  the  wire  in  question 
would  be  250  X  250  =  62,500  circular  mills. 


FOR  MANAGERS  AND  OPERATORS 


49 


The  circular  mill  area  of  any  round  wire  may  be  found  by  meas- 
uring its  diameter  in  thousandths  of  an  inch,  using  a  micrometer 
caliper  or  wire  gauge  for  the  purpose,  and  multiplying  the  meas- 
urement thus  obtained  by  itself. 

There  are  several  methods  of  measuring  wires.  The  ac- 
cepted standard  for  wire  measurement  in  this  country  is  the 
American  Gauge,  commonly  known  as  the  "Brown  &  Sharpe 
Gauge,"  and  in  practice  dubbed  the  "B.  &  S."  gauge,  the  same 
being  illustrated  in  Fig.  7. 

In  using  this  tool  it  is  the  slot  and  not  the  round  hole  that  de- 
termines the  size  of  the  wire,  and  while  the  wire  must  not 
actually  bind  in  the  slot,  it  must  fit  snugly.  The  gauge,  if  it 


Figure  7. 

be  a  good  one,  will  have  the  width  of  each  slot,  or,  in  other 
words,  the  diameter  of  the  wire  which  fits  the  slot,  stamped 
opposite  each  slot  on  one  side  of  the  gauge,  and  the  number 
of  the  wire  stamped  opposite  the  slot  on  the  other.  In  Fig.  7 
it  is  the  wire  number  side  we  see.  The  diameter  in  thousandths 
of  an  inch  is  the  same  thing  as  the  diameter  in  mills.  For 
instance,  No.  16  wire  has  a  diameter  of  fifty-one  thousandths 
of  an  inch,  or,  in  other  words,  51  mills,  the  term  thousandths 
of  an  inch  and  mills  being  interchangeable. 

One  of  the  most  convenient  and  at  the  same  time  most 
accurate  methods  of  measuring  wire  is  by  means  of  a  mi- 
crometer caliper.  See  Fig.  8.  These  calipers  may  now  be 
had  with  the  wire  size  and  their  equivalents  in  mills  (thou- 


50  MOTION    PICTURE    HANDBOOK 

sandths  of  an  inch)  stamped  thereon.  For  instance,  in  the 
illustration  we  see  "4/0,"  with  460.0  opposite  it,  which  means 
that  0000  (called  "four  0")  wire  is  460  mills  (460  thousandths 
of  an  inch)  in  diameter.  These  tools  are  expensive,  but,  on 
the  other  hand,  they  are  mighty  good  articles  to  own,  and 
ought  to  be  included,  in  one  form  or  another,  in  every  oper- 
ator's tool  kit. 


Figure  8. 

For  measuring  very  small  wires,  such  as  the  strands  of  an 
asbestos-covered  wire  (usually  No.  30  or  31),  the  slot  wire 
gauge  is  not  very  reliable  except  in  the  hands  of  an  expert. 
If  you  have  no  micrometer  caliper  it  is  better  to  have  a 
machinist  make  the  measurement  for  you  with  his.  Have 
measurements  made  of  three  or  four  strands  from  different 
parts  of  the  wire. 

For  most  purposes,  however,  the  wire  gauge,  in  conjunction 
with  the  wire  capacity  table,  page  42,  will  answer  all  purposes. 

Insulation 

WHEN  there  is  a  difference  in  potential  maintained 
between  two  wires  of  an  electric  circuit  these  wires 
have  an  affinity  for  each  other  and  current  seeks 
constantly  to  pass  from  one  to  the  other.  The  purpose  of 
insulation  is  to  prevent  this  and  to  keep  the  wires  from 
coming  into  electrical  contact  with  any  object  which  might 
furnish  an  electrical  path  to  a  wire  of  opposite  polarity  at- 
tached to  the  same  dynamo.  Such  a  path  may  be  found 
through  the  ground  or  through  any  current-carrying  material 
having  electrical  contact  with  wires  of  opposite  polarity. 
In  short,  insulation  is  to  protect  the  potential  of  or  on  a 
wire  interference  by  any  outside  source. 


FOR   MANAGERS   AND   OPERATORS  51 

As  we  have  already  seen  (page  38),  various  metals  offer 
varying  resistance  to  the  passage  of  electric  current.  Not 
only  is  this  true,  but  various  materials  other  than  metals 
offer  varying  resistance  to  the  passage  of  electric  current, 
and,  while  there  is  no  material  which  is  a  non-conductor — 
that  is  to  say,  through  which  electric  current  cannot  be 
forced  if  the  pressure  (voltage)  be  raised  sufficiently  high, 
still  there  are  materials  which  are  considered!  and  treated 
as  non-conductors,  because  no  ordinary  voltage  will  force 
current  through  them.  These  substances  are  called  "insulat- 
ing materials,"  at  the  head  of  which  stand,  in  the  order 
named,  glass,  procelain,  and  rubber.  Various  natural  sub- 
stances such  as  marble  and  slate  form  excellent  insulating 
materials,  and  asbestos,  when  dry,  is  also  a  very  good  in- 
sulator. There  are  also  various  insulating  compounds,  the 
composition  of  which  are  trade  secrets.  In  practice  these 
compounds  are  used  to  saturate  some  kind  of  braided  or 
other  material  which,  after  being  so  saturated,  is  used  for 
weatherproof  insulation  on  wires  to  be  used  out  of  doors,  or 
to  reinforce  the  rubber  insulation  of  rubber  covered  wires. 

Procelain  is,  for  the  most  part,  used  to  line  holes  in  brick 
or  other  walls  through  which  it  is  necessary  to  pass  wires 
and  for  knobs  to  carry  wires  which  are  run  in  open  circuit 
through  the  air,  or  along  walls.  Rubber,  on  the  other  hand, 
is,  for  the  most  part,  used  for  inner  insulation  of  what  is 
called  "rubber  covered"  insulation  of  wires.  Glass  is  used 
only  for  pole  insulators  on  low  potential,  owing  to  its  fragile 
nature. 

Rubber  covered  wire  consists  of  tinned  copper  wire  with 
a  covering  of  rubber  or  rubber  compound  of  homogeneous 
character,  reinforced  by  an  outer  covering  of  braided  cotton 
soaked  in  preservative  insulating  compound.  Where  copper 
wire  is  covered  with  any  of  the  rubber  compounds  the  tin- 
ning of  the  wire  is  very  necessary,  since  the  sulphur  uni- 
versally present  in  rubber  insulation  is  likely  to  combine 
with  the  copper  and  in  a  short  time  the  wire  would  be  cor- 
roded, and  either  very  greatly  weakened  or,  if  a  small  wire, 
entirely  destroyed.  The  tinning  of  the  wire  prevents  thij, 
since  tin  will  not  combine  with  sulphur  and  the  rubber  in- 
sulation has  no  effect  upon  it. 

It  is  not,  however,  the  purpose  of  this  book  to  go  into  an 
exhaustive  treatise  on  insulation  materials,  but  merely  to  give 
the  operator  a  general  understanding  of  the  proposition. 

The  current  must  be  confined  to  the  wire  and  made  to  pass 
from  the  positive  to  the  negative  through  the  paths  provided, 


52  MOTION    PICTURE   HANDBOOK 

and  through  them  only,  the  said  paths  being  motors,  in- 
candescent globes,  arc  lamps,  etc.  The  strength  of  insulation 
must  increase  with  the  potential,  and  its  kind  may  vary  with 
the  service.  For  instance:  the  insulation  known  as  "weather- 
proof" may  be  used  where  the  wires  are  stretched  in  open 
air  on  out-door  circuits.  On  the  other  hand,  for  interior 
work  while  this  same  insulation  may  still  be  used,  under- 
neath it  and  next  the  wire  there  must  be  a  coating  of  pure 
rubber  or  rubber  compound.  The  insulation  then  becomes 
what  is  known  as  "rubber  covered."  Its  disadvantage  lies 
in  the  fact  that  rubber  deteriorates  rapidly  under  the  influence 
of  even  moderate  heat,  and  is  immediately  destroyed  by  any- 
thing like  high  temperature.  The  necessary  strength  of  the 
insulation,  either  weatherproof  or  rubber  covered,  will  depend 
upon  the  voltage. 

There  are  several  ways  of  testing  the  insulation  of  wires, 
the  test  here  given  being  that  required  by  the  National 
Board  of  Fire  Underwriters  for  rubber  covered  wire. 

TESTING    INSULATION 

Any  one-foot  sample  of  completed  covering  must  show  a 
dielectric  (dielectric  is  defined  as  any  substance  or  medium 
that  transmits  the  electric  force  by  a  process  different  from 
conduction,  as  in  the  phenomena  of  induction;  a  non-con- 
ductor separating  a  body  electrified  by  induction  from  the 
electrifying  body)  strength  sufficient  to  resist,  for  a  period  of 
five  minutes,  the  application  of  voltage  proportionate  to  the 
thickness  of  the  insulation,  in  accordance  with  the  following 
table: 

TABLE   NO.  3 

Breakdown  test  on   1   foot 
Thickness  in  64th  inches  Volts   A.   C. 

1  3000 

2  6000 

3  9000 

4  11000 

5  13000 

6  15000 

7  16500 

8  18000 
10  21000 
12  23500 
14  26000 
16  28000 


FOR   MANAGERS    AND    OPERATORS  53 

In  making  the  foregoing  test  the  source  of  electro-motive 
force  (voltage)  must  be  a  transformer  of  at  least  one  kilowatt 
capacity.  The  application  of  the  electro-motive  force  shall 
be  made  at  3000  volts  for  five  minutes,  and  then  the  voltage 
must  be  increased  by  steps  of  not  more  than  3000  volts  each, 
the  voltage  of  each  step  being  held  for  five  minutes  until 
the  maximum  for  a  given  thickness  of  insulation  is  had,  or 
until  there  is  a  rupture  of  the  insulation.  The  test  for  die- 
lectric strength  must  be  made  on  wire  which  has  been 
immersed  in  water  for  seventy-two  hours,  one  foot  of  the 
wire  under  test  to  be  submerged  in  a  conducting  liquid  held 
in  a  metal  trough,  one  of  the  transformer  terminals  being 
connected  to  the  copper  of  the  wire,  and  the  other  to  the 
metal  of  the  trough. 

There  are  two  types  of  weather-proof  wire,  viz.:  weather- 
proof and  slow-burning  weather-proof.  The  insulation  of 
the  slow-burning  weather-proof  consists  of  two  coatings,  one 
of  which  is  fire-proof  in  character,  while  the  other  is 
not.  The  fire-proof  coating  is  on  the  outside  and  com- 
prises about  six-tenths  of  the  total  thickness  of  the  insula- 
tion. The  complete  covering  for  sizes  of  wire  from  No.  14 
to  No.  0000  varies  from  3/64  to  5/64  of  an  inch.  The  fire- 
proof insulation  is  not  as  susceptible  to  fire  as  is  ordinary 
weather-proof,  nor  does  it  as  readily  soften  under  the  influ- 
ence of  heat.  It  is  not  suitable,  however,  for  outside  work, 
being  intended  for  interior  work  in  dry,  warm  places  such  as 
shops  and  factories.  There  is  another  type  of  wire  insulation 
called  "slow-burning,"  which  is  still  more  fire-proof  than  is 
the  slow-burning  weather-proof.  It  is  intended  to  be  used 
in  very  hot  places  where  ordinary  insulation  would  soon  per- 
ish. The  insulation  of  weather-proof  wire  should  consist 
of  at  least  three  layers  of  braid,  each  of  which  is  thoroughly 
saturated  with  a  dense,  moisture-prool;  compound,  applied 
in  such  manner  as  to  drive  any  atmospheric  moisture  out  of 
the  cotton  braiding,  thereby  securing  a  covering  to  a  great 
degree  water-proof  and  of  high  insulating  power.  The  outer 
surface  of  this  insulation  is  pressed  down  to  a  hard,  dense 
surface.  This  wire  is  for  use  out  of  doors  where  moisture 
is  certain  and  where  fire-proof  qualities  are  not  necessary. 
In  general,  weather-proof  wires  can  be  used  only  where  the 
insulating  supports  on  which  the  wire  is  mounted  are  de- 
pended on  for  insulation,  the  covering  being  regarded  simply 
as  a  precaution  against  accidental  contact  with  other  wires  or 
other  objects. 


54  MOTION    PICTURE    HANDBOOK 

From  the  foregoing  it  will  readily  be  understood  that  the 
principal  difference  between  rubber-covered  and  other  in- 
sulation lies  in  the  fact  that  the  rubber-covered  insulation 
may  be  depended  upon  entirely  for  insulating,  whereas  the 
others  must  depend,  at  least  to  a  considerable  extent,  on  the 
insulating  supports  for  their  insulation.  Rubber-covered  wire 
may  be  used  in  any  place  that  weather-proof  would  be  allow- 
able, but  not  in  places  where  slow-burning  insulation  would 
be  required.  Double  braid  rubber-covered  wire  is  the  only  kind 
that  may  be  used  in  conduits,  where  the  two  wires  of  the  circuit 
lie  side  by  side.  So  far  as  the  carrying  capacity  of  copper  be 
concerned  it  makes  absolutely  no  difference  what  the  insula- 
tion be  composed  of.  The  reason  that  rubber-covered  wire 
is  rated  at  lower  capacity  than  weather-proof  is  by  reason 
of  the  fact  that  rubber  is  easily  injured  by  even  moderate 
heat,  hence  when  it  is  used  a  high  margin  of  safety  is  main- 
tained. 

Under  no  circumstances  is  it  permissible  to  use  other  than 
wire  having  rubber-covered  insulation  inside  of  conduits. 

Wire  Systems 

IT  is  highly  desirable  that  the  operator  have  a  good  work- 
ing knowledge  of  the  various  wire  systems  with  which 
he  is  likely  to  come  in  contact.  It  is  not  the  purpose  of 
this  work  to  make  the  operator  a  wireman,  or  an  electrician 
for  that  matter,  but  merely  to  give  him  a  fairly  comprehen- 
sive general  idea  of  the  action  of  electric  current  and  the 
appliances,  including  the  wire  systems,  with  which  he  will 
have  to  do. 

On  the  road,  particularly  when  playing  small  towns,  the 
operator  may  be  called  upon  to  connect  to  any  one  of  the 
several  different  wire  systems,  and  unless  posessed  of  knowl- 
edge he  will  be  unable  to  proceed  with  any  degree  of  certainty 
or  confidence. 

There  is  one  wire  system  with  which  it  is  impractical — I 
might  even  say  impossible — to  connect  a  projection  arc, 
viz,  the  series  arc  system.  This  system  is  used  only  for 
street  arc  lighting.  Instead  of  two  wires  it  only  has  one,  and 
each  lamp  carries  the  entire  amperage  of  the  system,  or 
circuit.  The  voltage  of  the  series  arc  system  will  depend  upon 
the  number  of  lamps,  there  being  an  added  pressure  of  about 
50  volts  for  each  lamp,  so  that  a  circuit  supplying  ten  lamps 
would  have  a  pressure  or  voltage  of  50  X  10  =  500  volts,  whereas 
if  there  were  eleven  lamps  the  pressure  would  be  SOX  11=550, 


FOR  MANAGERS  AND  OPERATORS 


55 


and  so  on.  Do  not  attempt  to  connect  your  projection 
lamp  to  the  series  arc  system,  because  if  you  do  you  will 
fail;  also  you  will  cause  serious  trouble,  and  may  succeed 
in  getting  yourself  badly  shocked,  or  possibly  even  killed. 
Fig.  9  is  a  diagrammatic  representation  of  a  10  lamp  series 
arc  system. 


?  : 

<p             <j? 

rh            rh 

T            -^~ 

T 

M^            T 

Figure  9. 

There  was  at  one  time  a  system  called  the  "series-mul- 
tiple" and  another  called  the  "multiple-series,"  but  with  these 
it  is  unnecessary,  I  think,  to  deal,  since  they  have  been 
practically  if  not  entirely  abandoned. 

TWO-WIRE  SYSTEM 

The  "multiple  arc  system,"  also  called  the  "two-Jwire 
system,"  is,  to  all  intents  and  purposes,  the  only  one  with 
which  the  operator  comes  into  contact,  the  three-wire  system 
being  but  a  variation  of  the  two-wire  system,  so  far  as  elec- 
trical action  and  practical  effect  be  concerned. 


Figure  10. 

In  Fig.  10  we  see  diagrammatic  representation  of  what  is 
varyingly  styled  the  "multiple  arc,"  "parallel"  and  "two- 
wire"  system.  The  heavy  lines  represent  mains  coming  from 


56  MOTION    PICTURE    HANDBOOK 

the  power  house,  the  less  heavy  ones,  D-D,  branch  mains 
feeding  a  district  or  street,  and  the  thin  lines,  E-E-E,  house, 
store,  theatre  circuits,  etc.  In  theory  the  current  flows  out 
from  the  dynamo  on  the  positive  wire,  through  the  various 
lamps,  etc.,  to  the  negative,  and  back  on  it  to  the  dynamo. 

In  one  of  the  house  circuits  a  projection  lamp  is  attached, 
all  switches,  fuses,  etc.,  being  omitted  for  convenience.  As- 
suming that  the  system  carries  not  more  than  500  volts  we 
may  attach  a  projection  lamp  to  the  wires  at  any  point, 
provided  (a)  the  wires,  switches,  etc.,  be  large  enough  to 
carry  the  current  necessary  for  the  arc,  plus  whatever  else 
they  will  have  to  carry,  without  overload;  (b)  the  fuses  be 
large  enough  to  carry  current  for  the  arc,  plus  whatever 
else  it  will  have  to  carry;  (d)  provided  sufficient  resistance 
be  connected  in  series  with  the  lamp  to  reduce  the  line 
voltage  to  arc  voltage. 

If  the  system  be  D.  C.  the  voltage  will  not,  in  any  event, 
exceed  500,  and,  except  in  the  case  of  power  lines  for  street 
car  service,  seldom  goes  above  22§. 

If  the  current  be  alternating  then  you  can  attach  your  pro- 
jection lamp  at  any  point,  provided  the  same  precautions  be 
taken  as  before  named  for  D.  C.,  but  if  the  line  be  what  is 
called  high  tension  (1000  volts  or  more),  then  you  can  only  attach 
your  projection  lamp  on  the  secondary  side  of  a  transformer. 
In  this  connection  the  traveling  operator  should  always  have 
a  copy  of  McGraw's  Electrical  Directory,  which  is  for  sale 
by  McGraw  Publishing  Company,  239  West  Thirty-ninth  Street, 
New  York  City,  costs  $10  a  year,  and  gives  particulars  of  every 
light  plant  in  the  country.  If  he  is  not  the  possessor  of  this  book, 
then  the  first  thing  for  him  to  do  upon  entering  a  town  is  to 
call  up  the  power  house  and  ask:  (a)  the  kind  of  system; 
(b)  voltage  of  the  system;  (c)  if  the  show  is  to  be  given  in  a 
church,  school  house,  or  hall,  and  the  current  is  A.  C.,  and 
whether  or  not  the  transformer  supplying  the  building  in 
which  the  show  is  to  be  given  is  large  enough  to  supply  the 
projection  arc,-  plus  whatever  else  it  has  to  supply. 

THREE-WIRE  SYSTEM 

The  three-wire  system  is  a  very  popular  and  widely  used 
method  of  electric  light  and  power  distribution.  Its  basic 
principle  is  the  fact  that  if  two  batteries  or  two  generators, 
of  the  same  voltage,  be  connected  in  series  with  each  other, 
the  voltage  between  the  positive  terminal  of  one  generator 


FOR   MANAGERS    AND    OPERATORS 


57 


or  battery  and  the  negative  terminal  of  the  other  generator 
or  battery  will  be  double  the  voltage  of  either  battery  or 
dynamo  separately.  Thus  if  each  dynamo  be  a  110  volt 
generator,  then  the  voltage  between  the  positive  of  one 
machine  and  the  negative  of  the  other  would  be  220  volts, 
but  if,  at  the  same  time,  the  voltage  be  taken  across  the 
positive  and  negative  brush  of  either  machine  separately, 
the  reading  will  be  only  110,  or  whatever  the  voltage  of  the 
individual  machines  may  be.  It  therefore  follows  that  if  a 
wire  be  attached  to  the  positive  of  one  generator  and  the 
negative  of  the  other  generator,  the  voltage  between  these 
two  wires  will  be  double  the  voltage  of  either  generator 
taken  separately,  and  if  a  third  wire  be  attached  to  the 
jumper  connecting  the  two  generators  the  voltage  between 
either  of  the  outside  wires  and  the  center  wire  (called  the 
"neutral")  will  only  be  the  voltage  of  the  individual  dynamo, 
or  half  the  pressure  between  the  two  outside  wires. 


ft 


r* 


Figure  11. 

In  Fig.  11  A  and  B  are  110  volt  generators;  C  is  a  jumper 
connecting  the  negative  terminal  of  machine  A  with  the 
positive  terminal  of  machine  B;  D  is  a  wire  attached  to 
jumper  C,  the  same  being  called  the  "neutral"  wire:  E  is  a 
wire  attached  to  the  positive  terminal  of  generator  A;  F  is  a 
wire  attached  to  the  negative  terminal  of  generator  B;  G  is  a 
voltmeter  attached  between  wires  E  and  D;  H  is  another  volt- 
meter attached  between  D  and  F,  and  I  is  a  third  voltmeter 
attached  between  wires  E  and  F.  Assuming  generators 
A  and  B  to  be  110  volt  machines  then  voltmeters  G  and  H 
will  each  read  110,  whereas  voltmeter  I  will  read  220.  If 


58  MOTION    PICTURE    HANDBOOK 

generators  A  and  B  were  each  70  volt  machines,  then  volt- 
meters G  and  H  would  each  read  70,  whereas  voltmeter  1 
would  read  140.  Still  referring  to  Fig.  11,  J,  K,  L,  M,  and  N 
are  ordinary  16  c.p.  incandescent  globes,  requiring,  let  us 
assume,  half  an  ampere  of  current  each. 

The  electrical  action  is  as  follows:  For  the  moment 
switching  off  globes  J,  L  and  N  let  us  consider  only  lamps 
K  and  M.  Under  this  condition  a  half  ampere  of  current  at 
220  volts  pressure  would  pass  out  from  the  positive  brush  of 
generator  A,  along  wire  E  to  lamp  K,  which  is  a  110  volt 
lamp,  as  is  also  lamp  M,  therefore  the  combined  resistance 
of  the  two  lamp  filaments  will  be  just  sufficient  to  allow  a 
half  ampere  of  current  to  flow.  Thus  a  half  ampere  passes 
through  lamp  K,  into  the  neutral  wire  and  back  toward  the 
generator,  but  instead  of  traveling  on  and  into  jumper  C, 
it  switches  off,  goes  through  lamp  M  and  thence  back  on 
wire  F  to  the  negative  terminal  of  generator  B.  In  other 
words,  lamps  K  and  M  burn  in  series  with  each  other,  and 
under  this  condition  no  current  at  all  passes  over  the  neutral 
wire  between  lamp  M  and  jumper  C. 

Now,  taking  a  step  further,  let  us  consider  J,  K  and  L. 
Each  lamp  requires,  let  us  assume,  55  watts;  therefore,  55  X 
3  =  165  watts,  divided  by  110=:  \y2  amperes  passes  out  on 
wire  E,  through  the  lamps,  into  the  neutral  and  starts  back 
thereon,  but  55  watts  (^  ampere)  passes  through  lamp  M, 
and  another  55  watts  (l/2  ampere)  passes  through  lamp  N 
into  wire  F,  which  accounts  for  one  ampere,  and  leaves  55 
watts  (l/2  ampere)  yet  to  be  accounted  for,  which  must  pass 
back  to  the  negative  terminal  of  generator  A,  over  the  neu- 
tral wire,  D,  so  that  under  this  condition  (called  an  "un- 
balanced system")  we  have  \l/2  .amperes  flowing  on  wire 
E,  1  ampere  on  wire  F,  and  l/2  ampere  on  wire  D.  For  the 
sake  of  added  clearness  I  have  mapped  out  the  course  of  the 
current  with  arrows  which  indicate  the  current  flow. 

In  figuring  the  amperage  of  a  110-220  volt  three-wire  system 
remember  this: 

If  you  have  110  volt  lamps  or  motors  on  one  side  rated 
at  a  given  number  of  amperes  you  can  add  110  volt  apparatus 
of  equal  capacity  on  the  other  side  without  increasing  the 
number  of  amperes  flowing  in  the  system.  The  electrical 
effect  is  the  same  as  though  you  removed  the  110  volt  ap- 
paratus from  the  first  side  and  substituted  220  volt  apparatus 
of  double  h.  p.,  connected  between  the  two  outside  wires. 

With  a  three-wire  110-220  volt  system  either  110  volt  or 
220  volt  apparatus  may  be  used.  If  you  connect  a  motor  or 


FOR   MANAGERS    AND    OPERATORS  59 

lamp  from  either  outside  wire  to  the  neutral  it  must  be  a 
110  volt  motor  or  lamp;  if  you  connect  a  motor  or  lamp 
from  outside  to  outside  wire  it  must  be  a  220  volt  motor  or 
lamp,  always  assuming  the  generators  to  be  110  volt  ma- 
chines, as  they  are  in  practically  all  cases. 

The  ideal  condition  with  a  three-wire  system  presumes  it 
to  be  perfectly  "balanced,"  meaning  by  this  that  110  volt 
apparatus  (motors  and  lamps)  drawing  the  same  total  am- 
perage be  connected  to  both  sides.  If  in  a  light  and  power 
system  there  is  110  volt  apparatus  connected  to  one  side, 
wires  E  and  D,  Fig.  11,  drawing  a  total  of  240  amperes,  then 
there  should  be  110  volt  apparatus  connected  to  the  other 
side,  wires  D  and  F,  Fig.  11,  sufficient  to  use  240  amperes. 
Under  this  condition  the  system  would  be  perfectly  bal- 
anced, and  all  apparatus  would  work  in  series,  so  that,  so  far 
as  the  actual  operation  of  the  lamps  and  motors  be  con- 
cerned, the  neutral  wire  might  be  disconnected  from  the 
dynamo  entirely.  In  other  words,  if  the  neutral  fuse  at  the 
power  house  blew,  or  was  removed,  there  would  be  no  effect 
at  all.  The  total  amperes  would  only  be  240. 

This  ideal  condition  is,  however,  seldom  or  never  real- 
ized in  practice.  There  is  practically  always  more  load  on 
one  side  than  on  the  other,  and  amperage  equal  to  the  dif- 
ference between  the  load  on  the  two  sides  flows  back  to  the 
generator  on  the  neutral  wire.  If  there  are  26400  watts 
being  used  on  one  side  and  24200  on  the  other,  then  26400  — 
24200  =  2200 -M 10  =  20  amperes  would  flow  back  to  the  gen- 
erator on  the  neutral  wire,  and  the  practical  effect  would  be 
that  one  generator  would  be  producing  20  amperes  more 
than  the  other. 

It  is  for  this  very  excellent  reason  that  heavily  loaded  systems 
often  object  to  projection  arcs  being  connected  to  one  side 
of  the  system.  Both  dynamos  are  working  up  to  their 
capacity,  and  if  a  projection  arc  pulling,  say,  40  amperes 
be  hitched  to  one  side  its  load  is  all  thrown  on  one  dynamo 
and  the  system  is  thus  unbalanced.  However,  if  the  opera- 
tor is  reducing  his  voltage  with  a  rheostat  it  would  not  help 
matters  in  the  least  to  connect  across  the  outside  wires, 
since,  although-  the  amperage  would  remain  the  same  the 
generators  must  put  out  double  the  amount  of  energy,  and 
instead  of  having  one  dynamo  loaded  that  much  heavier, 
we  have  both  carrying  an  additional  load  equal  to  amperage 
times  220,  one-half  of  which  is  carried  by  each  generator, 
which  represents  pure,  unadulterated  waste.  If  an  economizer, 
a  mercury  arc  rectifier,  or  a  motor  generator  set  be  used, 


60 


MOTION    PICTURE    HANDBOOK 


however,  then  it  is  different,  since  the  total  energy  taken 
from  the  lines  will  be  practically  the  same  when  connected 
across  on  220  as  it  would  on  one  (110  volt)  side. 

It  may  be  said  that,  as  a  matter  of  fact,  if  you  use  a  rheo- 
stat for  resistance  the  power  company  can  have  no  reasonable 
excuse  for  compelling  you  to  attach  your  projection  arc  to  the 
outside  wires  of  a  three-wire  system.  It  simply  costs  you  that 
much  more,  and  does  not  relieve  the  power  plant  in  the 
least;  in  fact  it  adds  to  the  total  load. 

The  operator  encounters  some  very  puzzling  questions  in 
connection  with  the  three-wire  system.  For  instance. 


D. 

/OftMf. 


Figure  12. 


In  Fig.  12  we  see  a  three-wire  system  fused  at  60  amperes. 
From  these  lines  are  taken  six  circuits  A,  B,  C,  D,  E,  and  F, 
five  of  which  have  apparatus  attached  to  them  requiring  10 
amperes  of  current  each.  Now  with  those  60  ampere  fuses 
would  it  be  possible  to  attach  a  25  ampere  projection  arc 
to  the  idle  circuit  F?  At  first  glance  you  may  say  No;  you 
are  already  pulling  50  amperes,  since  5  X  10  makes  50,  and 
right  there  you  make  a  mistake,  because  you  are  not  doing 
anything  of  the  sort.  You  are  pulling  a  total  of  20  amperes 
across  the  outside  wires,  and  10  additional  amperes  on  one 
side,  so  that  fuse  1  carries  30,  fuse  2  10  and  fuse  3  20  amperes, 
therefore  on  the  side  that  the  idle  circuit  is  on  you  are  only 
pulling  20  amperes,  and  if  you  attach  a  25  ampere  arc  you 
will  still  have  a  leeway  of  15  amperes.  Why? 


FOR   MANAGERS    AND    OPERATORS  61 

The  answer  is  simple.  It  is  purely  a  question  of  wattage. 
One  side  has  110  volt  apparatus  requiring  a  total  of  20  X  HO 
=  2200  watts.  The  other  side  requires  30  X  HO  =  3300  watts. 
The  current  comes  out  on  wire  1,  at  220  volts  pressure.  It 
is  forced  through  the  110  volt  motor  and  lamps,  110  volts 
of  the  pressure  being  consumed  in  so  doing.  It  is  then  on 
the  neutral  wire,  still  30  amperes,  but  at  110  volts  pressure; 
therefore  it  still  has  power  equal  to  110X30  =  3300  watts. 
Now  the  neutral  is  negative  to  wire  1  but  positive  to  wire  3, 
and  wire  3  is  the  TRUE  negative  of  the  combination.  Therefore, 
there  is  still  the  inclination  to  seek  the  negative  (true  negative), 
but  the  apparatus  connecting  wires  2  and  3  only  requires 
110X20  =  2200  watts,  so  that  when  they  have  been  supplied 
10  amperes  10X110=1100  watts  remain,  and,  being  unable 
to  reach  the  true  negative,  wire  3,  must  pass  back  to  the 
generator  on  wire  2,  the  neutral,  and  thus  we  find  that  the 
apparatus  on  both  sides  has  been  supplied  by  the  30  amperes, 
and  in  such  manner  that  fuse  1  carries  30,  fuse  2  10,  and  fuse  3 
20  amperes. 

As  soon,  however,  as  we  attach  a  25  ampere  arc  to  F,  the 
10  amperes  overbalance  from  the  other  side  ceases  to  flow 
back  over  the  neutral  and  begins  to  burn  in  series  with  the 
arc,  which  makes  30  amperes  on  the  D,  E,  F  side,  plus  the 
added  15  amperes  required  to  make  up  the  25  ampere  arc,  or  a 
total  of  45  amperes,  so  that  we  have,  under  that  condition,  30 
amperes  on  the  A,  B,  C  side  outside  wire,  and  45  amperes  on 
the  D,  E,  F  side  outside  wire  and  15  amperes  flowing  out 
from  the  dynamo  on  the  neutral.  Therefore  our  60  ampere 
fuse  would,  as  a  matter  of  fact,  still  be  altogether  too  large 
to  properly  protect  the  apparatus.  It  would  require  a  40 
ampere  arc  to  work  fuse  3  to  capacity.  To  be  fused  absolutely 
right  under  those  conditions  we  should  have  a  30  ampere  fuse 
on  one  outside  wire,  a  45  ampere  fuse  on  the  other  and  a  15 
ampere  fuse  on  the  neutral,  but  this,  of  course,  is  never  done 
in  actual  practice,  since  the  load  carried  by  fuse  2  would  vary 
with  every  lamp  or  motor  shut  off  on  either  side,  and  the 
apparatus  is  supposed  to  be  protected  by  its  individual  circuit 
fuses. 

Notes  Now  don't  start  trying  to  tear  this  to  pieces  on 
technicalities.  It  is  under standdbleness  I  am  after,  rather  than 
strictly  technical  correctness. 

If  your  theatre  is  fed  by  a  three-wire  system  you  should 
see  to  it  that  the  two  sides  are  as  nearly  as  possible  balanced. 
If  they  were  perfectly  balanced  your  neutral  fuse  could  blow 
without  affecting  the  lights  in  your  house,  but  if  the  neutral 


62  MOTION    PICTURE    HANDBOOK 

fuse  blows  and  the  system  is  unbalanced  then  the  effect  is 
that  of  forcing  the  lights  on  one  side  above  candle  power 
while  those  on  the  other  side  will  burn  below  candle  power. 

FIGURING  WIRE  SIZES 

To  figure  wire  sizes  for  three-wire  circuits  you  should  pro- 
ceed the  same  as  for  ordinary  two-wire  systems  (page  55), 
considering  only  the  two  outside  wires  and  the  amperage 
necessary  to  operate  the  apparatus  at  220  volts;  then,  having 
determined  the  size  of  the  two  outside  wires,  make  the  center 
wire  the  same  size. 


Go  to  your  work  each  day 
as  though  it  were  your 
first  day  on  a  new  job 
and  you  had  to  make  good. 


FOR    MANAGERS    AND    OPERATORS  63 


Switches 

THERE    are    a    few    points    of    importance    concerning 
switches  to  which  the  operator's  attention  should  be 
forcefully  directed.     I  emphasize  the  "forcefully"  be- 
cause I   have  seen   these  things  neglected,  with   consequent 
heating  and  even  burning  at  the  switch  contacts,  in  all  too 
many  operating  rooms. 

In  Fig.  13  we  see,  at  the  left,  an  ordinary  single-pole,  single- 
throw  knife  switch,  in  which  A  is  the.  blade  of  the  switch,  B 
the  handle,  C  the  contact,  D  the  hinge,  E-E  the  terminals  to 
which  the  wires  are  attached,  and  F  the  insulating  base, 
which  may  be  slate,  porcelain,  marble  or  any  other  high 
grade  insulating  material  suitable  for  the  purpose.  At  the 
right  is  a  single-pole  switch  with  a  second  contact,  so  that 


Figure  13. 

blade  A  may  be  thrown  over  to  make  a  contact  on  the  other 
side.  Instead  of  being  a  single-pole,  single-throw  switch  it  thus 
becomes  a  single-pole  double-throw  switch,  or,  as  ordinarily  ex- 
pressed, a  S.  P.  D.  T.  switch. 

If  a  switch  has  two  blades,  connected  by  a  cross  bar  of 
insulating  material  to  which  the  handle  is  attached,  as  per  A, 
Fig.  14,  then  it  is  a  "double-pole"  instead  of  a  single-pole 
switch.  If  it  has  three  blades,  as  per  B,  Fig.  14,  it  would  be 
a  "triple-pole"  or  "three-pole"  switch,  and  so  on.  C,  Fig.  14, 
shows  a  double-pole  single-throw  (D.  P.  S.  T.)  switch 
equipped  with  contacts  for  knife-blade  cartridge  fuses,  such 
as  are  shown  at  B,  Fig.  22;  D  shows  a  double-pole 
single-throw  switch  with  ferrule  contacts  for  cartridge  fuses. 
Switches  with  contacts  for  link  fuses  may  be  had  instead  of 
for  cartridge  or  plug,  and  may  be  used  for  projection  cir- 
cuits, if  such  circuits  are  to  be  protected  by  link  fuses,  thus 


64 


MOTION    PICTURE    HANDBOOK 


obviating  the  necessity  for  a  separate  fuse  block;  E  and  F 
show  types  of  porcelain  base  single-throw,  double-pole 
switches  with  plug  fuse  receptacles.  These  switches  are 
called  "panel  cut-outs,"  and  may  be  used  to  control  individual 
circuits  of  low  amperage. 


Figure  14. 


Inclosed  Switches.— An  inclosed  switch  is  one  with  an  in- 
dividual covering,  usually  of  sheet  metal,  which  entirely  in- 
closes the  switch-blades,  contacts,  etc.  This  is  the  type  used 
for  the  projection  machine  table  switch.  The  covering  is  to 
protect  the  operator  from  accidental  contact  with  live  parts 
of  the  switch,  and  to  prevent  accidental  short  circuits.  With 
inclosed  switches  it  is  important  the  covering  be  so  made 
that  it  cannot  come  into  contact  with  the  live  parts  of  the 
switch,  since  if  both  blades  or  two  contacts  of  opposite  polar- 
ity come  into  contact  with  the  metal,  a  direct  short  circuit  is 
formed. 

In  connecting  inclosed  switches  it  is  very  much  better  that  the 
blade  end  of  the  switch  be  dead  when  the  switch  is  open.  In 
fact,  that  rule  applies  to  all  switches,  though  sometimes  circum- 
stances prevent  its  being  adhered  to. 

Proper  Location  of  Switches. — This  is  a  difficult  matter  to 
deal  with  intelligently,  since  local  conditions  must  very 


FOR   MANAGERS    AND   OPERATORS  65 

largely  govern.  In  general,  however,  it  may  be  said  that  the 
house  switchboard  should  be  so  located  that  the  man  in 
charge  will  have  an  unobstructed  view  of  the  screen  when  at 
the  switchboard.  This  is  of  particular  importance,  since 
otherwise  it  will  be  found  very  difficult  properly  to  handle 
the  lights  at  the  beginning  .and  end  of  the  show,  or  at  the 
beginning  or  end  of  individual  reels. 

Switches  governing  emergency  lights  (exit  lights  and  all  lights 
kept  burning  during  the  performance)  should  under  no  circum- 
stances be  placed  on  the  main  switchboard.  You  can  never  tell 
what  an  excited  man  will  do,  and  in  case  of  fire,  people  inside  the 
auditorium,  including  employes,  are  usually  excited. 

Place  the  emergency  light  switches  in  the  box  office  where  no- 
body can  get  at  them  but  the  ticket  seller,  and  make  him  or  her 
directly  responsible  for  their  proper  handling. 

In  the  operating  room  local  conditions  will  govern  the  plac- 
ing of  the  switches,  but  it  may  be  said  in  general  there  is 
nothing  to  be  gained  by  making  things  inconvenient  for  the 
operator,  and  wrongly  located  switches  often  cause  much 
entirely  unnecessary  labor  .and  annoyance. 

The  operating  room  incandescent  lights  should  be  governed  by 
one  switch,  -located  where  it  can  easily  be  reached  from  operating 
position  at  either  machine.  There  should  also  be  individual  snap 
switches  on  each  lamp  socket. 

This  is  of  much  importance,  because  it  is  utterly  impractical, 
not  to  say  impossible,  to  have  high  class  projection  with  incan- 
descent lights  burning  in  the  operating  room,  and  the  operator  is 
much  more  likely  to  extinguish  his  lights  if  there  is  a  switch 
handily  located  with  which  he  can  put  them  all  out  at  one  opera- 
tion than  he  is  to  put  out  two  or  three  lights  by  means  of  their 
individual  socket  switches.  This  is  one  of  the  seemingly  simple 
points  which  is  of  great  importance  in  its  bearing  on  results  on 
the  screen. 

NEVER  install  a  knife  switch  in  such  way  that  its  handle 
moves  upzvard  in  opening  the  switch. 

If  it  be  a  single-throw  switch,  install  it  so  the  handle  hangs 
down  when  the  switch  is  open.  If  it  be  a  double-throw  switch 
install  it  so  the  handle  swings  sideways.  This  obviates  the 
danger  of  the  switch  accidentally  falling  shut. 

Uses  of  Types  of  Switches. — The  use  of  the  single-pole 
switch  except  for  certain  purposes  is  prohibited  by  Under- 
writers' rules,  and  none  of  those  purposes  exist  in  theatres, 
I  think,  except  that  the  single-pole  switch  is  of  use  in  the 


66  MOTION   PICTURE   HANDBOOK 

making  of  certain  rheostat  connections,  as  will  be  explained 
under  another  heading. 

The  double-pole  single-throw  switch  is  the  type  ordinarily 
used  to  control  incandescent  and  projection  circuits,  and,  in 
fact,  for  practically  all  theatre  circuits,  except  those  con- 
trolled by  a  triple-pole,  or  by  a  double-pole,  double-throw 
switch.  The  triple-pole  single-throw  switch  is  used  to  con- 
trol three-wire  circuits  where  they  enter  the  theatre,  and 
wherever  else  the  three-wire  circuit  may  extend.  The  double- 
pole  double-throw  switch  is  used  in  certain  fuse  connections, 
as  will  be  explained  under  "Fuses."  It  is  also  of  use  for  con- 
necting two  separate  two-wire  supply  systems,  and  for  pro- 
jection circuit  connections  under  certain  conditions. 

Underwriters'  Rules  require  that  switches  have  certain  di- 
mensions, according  to  the  voltage  and  amperage  they  are  to 
handle.  Both  the  voltage  and  amperage  capacity  must  be 
stamped  on  some  part  of  knife  switches. 


Figure  15. 

Fig.  15  illustrates  how  switches  are  marked.  Reject  any 
switch  not  so  stamped.  A  switch  may  be  used  for  a  less  am- 
perage and  less  voltage  than  its  stamping,  but  never  for  higher 
voltage  or  amperage.  The  higher  the  voltage  the  farther 
apart  must  be  the  knives  of  the  switch,  and  the  longer  they 
must  be.  Two  hundred  and  fifty-volt  switches  are  the  kind 
almost  universally  used  in  theatres.  There  is  no  such  thing 
as  a  110- volt  switch,  the  requirements  for  110  and  220  being 
the  same. 

At  the  right  in  Fig.  -15  we  see  an  illustration  of  a  switch 
equipped  with  fuse  link  contacts.  This  is  the  kind  of  switch 
that  is  used  on  projection  circuits  where  the  circuit  is  con- 
trolled with  link  fuses. 

Care  of  Switches.— Referring  to  Fig.  13,  hinge  D  must  be 
kept  tig^ht — tight  enough  so  that  it  requires  a  slight  effort 
to  move  the  handle.  Contacts  C  must  be  kept  in  good  con- 
dition and  must  grasp  blade  A  firmly  when  the  switch  is 
closed.  If  these  contacts  become  loose  there  will  be  heating, 


FOR   MANAGERS   AND   OPERATORS  67 

loss  of  power  and  roughening  of  both  the  contacts  and  the 
blades,  as  well  as  an  increase  in  the  resistance  of  the  copper 
by  reason  of  continuous  heating.  It  is  very  important  that 
hinge  D  be  kept  tight,  because  otherwise  when  you  close  the 
switch  the  blade  is  likely  not  to  strike  contacts  C  squarely 
and  enter  quickly,  with  consequent  arcing  and  burning  of  the 
copper.  Use  a  little  common  sense  and  good  judgment  in  deal- 
ing with  your  switches.  Should  these  contacts  become  rough  by 
arcing,  they  may  be  carefully  smoothed  with  a  very  fine,  thin 
file,  or  a  piece  of  0  or  00  emery  cloth  wrapped  around  a  thin 
piece  of  metal.  It  is  important  that  the  cross  bar  of  the 
switch  be  kept  tight.  A  loose,  wobbly  switch  is  an  abom- 
ination, and  conclusive  evidence  of  a  careless,  sloppy  work- 
man. 

Metal  Cabinet. — All  operating  room  switches  and  others, 
except  the  stage  switchboard,  should  be  inclosed  in  a  metal 
cabinet,  Fig.  19,  Page  72,  equipped  with  a  door  which  auto- 
matically closes  either  by  power  of  the  springs  or  action  of 
gravity.  It  is  a  good  plan  to  examine  the  switches,  say,  once 
a  week,  tightening  all  loose  joints  and  cleaning  off  all  dust. 
This  may  best  be  done  either  with  a  bellows  or  brush. 


Switchboards 

IT  is  essential  that  both  the  theatre  manager  and  operator 
have  a  very  good  understanding  of  the  main  switchboard. 
In  many  of  the  larger  houses  the  main  switchboard  is  a 
large,  imposing  arrangement,  which  looks  very  formidable. 
As  a  matter  of  fact,  however,  these  boards  are  quite  simple 
and  easily  understood,  if  one  examine  them  closely,  keeping 
in  mind  his  knowledge  of  electrical  action.  On  Page  10  of 
the  "National  Electric  Code,"  a  copy  of  which  may  be  se- 
cured free  by  sending  stamped,  self-addressed  envelope  to 
the  National  Board  of  Underwriters'  office,  William  Street, 
New  York  City,  appear  the  following  rules,  which  must  be 
strictly  observed  in  the  installation  of  switchboards: 

a.  Must  be  so  placed  as  to  reduce  to  a  minimum  the  danger  of  communi- 
cating fire  to  adjacent  combustible  material. 

Switchboards  must  not  be  built  up  to  the  ceiling,  a  space  of  three  feet  being 
left,  if  possible,  between  the  ceiling  and  the  board.  The  space  back  of  the 
board  must  be  kept  clear  of  rubbish  and  not  used  for  storage  purposes. 

b.  Must  be  made  of  non-combustible  material. 

c.  Must  be  accessible  from  all  sides  when  the  connections  are  on  the  back, 
but  may  be  placed  against  a  brick  or  stone  wan  when  the  wiring  is  entirely 
on  the  face. 


68  MOTION    PICTURE    HANDBOOK 

If  the  wiring  is  on  the  back,  there  must  be  a  clear  space  of  at  least 
eighteen  inches  between  the  wall  and  the  apparatus  on  the  board,  and  even 
if  the  wiring  is  entirely  on  the  face,  it  is  much  better  to  have  the  board 
set  out  from  the  wall. 

d.  Must  be  kept  free  from  moisture. 

e.  Wires   with   inflammable    outer  braiding,    when  brought  close  together, 
as  in  the   rear  of  switchboards,  must,   when   required,  be  each  surrounded 
with  a  tight,   non-combustible  outer  cover. 

Flame  proofing  must  be  stripped  back  on  all  cables  a  sufficient  amount  to 
give  the  necessary  insulation  distances  for  the  voltage  of  the  circuit  on 
which  the  cable  is  used. 

The  proper  location  of  the  main  house  switchboard  will 
depend  entirely  upon  local  conditions,  and  may  only  be  prop- 
erly determined  by  considering  each  individual  case.  The 
location  which  will  be  suitable  in  one  theatre  might  not  be 
so  in  another.  In  fixing  the  location  the  manager  should  be 
guided  largely  by  the  items  "accessibility'*  and  "convenience,"  but 
it  is  essential  that  the  board  be  so  located  that  the  man  handling 
it  will  have  a  good  view  of  the  screen  or  of  the  stage  when  at  his 
post  of  duty.  This  latter  is  very  essential  to  the  best  manipula- 
tion of  the  lights,  particularly  if  there  be  vaudeville. 

In  some  theatres  the  house  switchboard  is  located  in  the 
operating  room,  but  this  I  do  not  consider  as  being  the  best 
practice.  The  house  switchboard  should  be  located  below, 
but  a  portion  of  the  .auditorium  lights  should  be  so  arranged 
that  they  may  be  handled  from  both  the  main  switchboard 
and  from  the  operating  room.  An  emergency  may  at  any 
time  arise  in  which  it  is  imperative  that  the  auditorium  be 
lighted  instantly,  as  for  instance,  in  case  of  fire.  This  can,  of 
course,  be  done  by  the  switchboard  tender  below,  but  there 
would  probably  be  more  or  less  delay  in  the  response,  and, 
moreover,  the  signal  bell  might  "go  wrong"  just  at  that  time. 
I  do  not,  however,  favor  the  placing  of  the  main  board  in  the 
operating  room  under  any  conditions. 

Except  there  be  good  reasons  for  not  doing  so,  every  cir- 
cuit in  the  theatre,  including  the  operating  room  and  stage 
feeders,  but  excepting  the  emergency  lights  (emergency 
lights  are  the  exit  lights  and  those  ordinarily  left  burning 
during  the  performance,  such  as  foyer,  hall-way  .and  side 
lights),  should  pass  through  the  main  house  switchboard. 

On  the  main  house  switchboard  should  be  (a)  the  main 
fuses,  located  ahead  (on  the  street  side)  of  everything,  ex- 
cept the  exit  and  emergency  lights,  and  carrying  the  entire 
house  load;  (b)  the  main  switch,  which  kills  everything  but 
the  exit  and  emergency  lights;  (c)  fuses  for  every  individual 
circuit  in  the  house,  including  the  operating  room  and  stage 


FOR   MANAGERS    AND    OPERATORS 


69 


feeders;  (d)  service  switches  for  every  individual  circuit,  ex- 
cept the  operating  room  and  stage  feeders;  (e)  a  switch  gov- 
erning all  auditorium  circuits  ordinarily  extinguished  during 
the  performance,  except  where  the  auditorium  lights  are 
handled  from  the  stage.  This  latter  clause,  however,  may 
be  considerably  modified  by  the  peculiarities  of  requirement 
in  individual  installation.  In  small,  strictly  moving  picture 
houses,  it  is  much  better  to  have  the  auditorium  lights  extin- 
guished .all  at  one  time,  rather  than  by  pulling  half  a  dozen 
small  switches.  In  large  houses,  however,  where  there  are 
many  incandescent  lights  and  circuits,  this  is  not  a  practical 
thing  to  do,  and  a  dimmer  should  be  used. 


Figure  16. 

In  Fig.  16  is  seen  both  a  diagrammatic  and  photographic 
representation  of  ,a  small  three-wire  switchboard,  or  "panel" 
board.  In  the  diagram,  A  is  the  fuse  contact,  B  the  main 
switch,  C-C  the  house  circuit  fuse  contacts,  and  D-D  the  ser- 
vice switches  on  the  individual  incandescent  circuits,  all  of 
which  are  seen  photographically  represented  at  the  right, 
excepting  that  the  main  switch  and  fuses  are  omitted.  Both 
in  the  diagram  and  photograph  you  will  take  note  of  the  screw 
heads  connecting  feeder  bars  to  the  circuit  bars.  This  is  the 
secret  of  the  whole  thing.  The  left  hand  bar  of  the  diagram 
crosses  three  bars  and  attaches  to  the  fourth;  the  center  bar 
crosses  one  bar  and  attaches  to  the  two  center  bars,  and  the 
right  hand  bar  attaches  to  the  lower  cross  bar.  Now  the  ap- 
plication of  a  little  horse  sense  to  this  will  show  you  that 
the  two  top  cross  bars  take  current  from  the  left  hand  out- 
side feeder,  or  "bus  bar,"  and  the  neutral,  which  forms  a  two- 
wire  circuit  leading  both  ways  from  the  connection.  The 


70 


MOTION   PICTURE   HANDBOOK 


FOR   MANAGERS   AND   OPERATORS  71 

two  lower  cross  bars  .attach  to  the  right  hand  outside  feeder, 
or  "bus  bar,"  and  the  neutral,  which  forms  another  circuit,  on 
"the  other  side"  of  the  system,  leading  both  ways  from  the 
contact. 

In  examining  any  switchboard,  just  look  at  the  contacts,  or 
the  screw  heads,  for  they  will  show  you  how  the  whole  thing 
is  connected.  It  is  very  easy,  after  you  have  a  little  practice, 
but  it  is  a  mighty  puzzling  thing  to  the  beginner. 

Fig.  17  is  the  representation  of  a  large,  somewhat  com- 
plicated board.  On  one  side  the  individual  circuits  are  in- 
dicated. Study  the  contacts  and  you  will  be  able  to  trace  out 
the  connections.  Taking  the  top  right  hand  switch,  'for 
example,  we  find  the  circuit  starts  off  as  a  three-wire  circuit, 
through  fuses  and  a  triple-pole  switch,  which  latter  controls 
the  circuits.  It  then  splits  into  two  two-wire  circuits,  each 
having  their  own  fuses,  because  fuses  must  always  be  estab- 
lished on  individual  circuits,  or  where  wire  sizes  change.  The 
lower  wire  of  the  upper  two-wire  circuit  and  the  upper  wire 
of  the  lower  two-wire  circuit  attach  to  the  neutral,  and  the 
upper  wire  of  the  upper  and  the  lower  wire  of  the  lower  two- 
wire  circuit  to  the  outside  wires  of  the  three-wire  circuit. 
Remembering  that  the  neutral  is  positive  to  one  outside  wire, 
and  negative  to  the  other,  we  instantly  see  that  the  two  upper 
and  two  lower  wires  are  mates,  that  is  to  say,  they  are  pairs, 
forming  two  two-wire  (multiple  arc)  circuits.  We  also  see 
that  we  cannot  extinguish  the  lights  on  one  circuit  without 
extinguishing  the  lights  on  the  other,  except  that  we  remove 
the  fuses  on  one  of  the  circuits,  this  latter  by  reason  of  ab- 
sence of  individual  circuit  service  switches. 

Just  below  the  center  of  the  board  is  a  bank  of  circuits 
tapped  off  as  two-wire  circuits  right  at  the  bus  bars.  By 
observing  the  location  of  the  screw  heads  we  see  which  side 
each  circuit  connects  to.  We  see  there  are  four  screw  heads 
in  each  outside  bus  bar  in  this  bank  of  two-wire  circuits, 
therefore  there  are  four  circuits  on  either  side,  and  these  cir- 
cuits, provided  each  carries  appliances  using  the  same  total 
amperage,  is  said  to  be  "balanced."  At  the  bottom  we  see  a 
three-wire  lead  with  fuses,  but  without  switch.  This  is  prob- 
ably the  stage  or  operating  room  lead,  which  should  not  have 
a  switch  on  the  main  house  board.  The  main  switch  and 
fuses  controlling  and  protecting  the  entire  board  are  not 
shown. 

In  the  smaller  theatres  it  is  common  practice  to  build  up  a 
switchboard  out  of  porcelain-base  panel  cutouts,  such  as  is 


72 


MOTION    PICTURE    HANDBOOK 


illustrated  in  Fig.  18.  Any  number  of  blocks  may  be  used. 
They  must  be  placed  in  a  substantial  metal  cabinet,  similar 
to  the  one  shown  in  Fig.  19.  Back  of  the  blocks  should  be  a 


Figure  18. 

layer  of  sheet  asbestos,  or  .asbestos  millboard,  not  less  than 
three-eighths  of  an  inch  thick.  If  properly  put  together  such 
a  board  is  just  as  efficient,  though  it  does  not  look  as  well, 
as  the  regular  board  built  on  a  slate  base.  Ahead  of  a  board 
of  this  kind  should  be  the  main  switch,  and  a  cutout  block 
carrying  the  main  fuses. 

Exit  and  Emergency  Light  Boards. — The  feeders  for  these 
circuits  must  be  tapped  to  the  main  feeders  on  the  street  side 
off  the  main  house  fuses. 

They  must  be  controlled  by  switches  located  in  the  box  office, 
and  by  no  other  switches. 

For  further  information  concerning  this  subject  see  Fig.  28, 
Pages  85  and  86. 


Figure  19. 

Illustrating    small    panel    boxes    and    switchboards. 


FOR   MANAGERS    AND    OPERATORS 


73 


Stage  Switchboard. — The  stage  switchboard  should  be 
located  on  the  proscenium  wall.  It  is  common  practice  to 
place  it  to  the  right  of  the  stage  as  one  looks  toward  the 
audience.  It  should  be  protected  by  a  substantially  con- 
structed iron  railing,  not  less  than  48  inches  high  and  located 
not  less  than  36  inches  from  the  face  of  the  board,  and  to  be 
securely  fastened  to  the  floor  in  such  manner  as  to  withstand 
a  heavy  shock,  as,  for  instance,  a  person  falling  violently 
against  it,  or  scenery  falling  on  it. 

All  fuses  on  a  stage  switchboard  must  be  approved  cartridge  or 
plug  type.  It  is  absolutely  forbidden,  under  any  circumstances, 
to  use  a  link  or  open  fuse  on  the  stage. 

The  stage  switchboard  should  carry  (a)  main  fuses  and 
main  switch  supplying  all  stage  circuits;  (b)  service  fuses 
and  switches  for  each  individual  circuit,  plainly  labeled  with 
name  of  circuit  it  controls,  thus:  "White  Foots,"  "Red 
Foots,"  "First  Borders,  White,"  "First  Borders,  Green,"  etc. 

Stage  switchboards  need  not  be  equipped  with  a  cabinet  and 
door,  but  every  precaution  must  be  observed  to  render  acci- 
dental contact  with  scenery  impossible.  The  utmost  care 
must  be  exercised  that  all  switch  contacts  and  wire  contacts 
and  fuse  contacts  be  kept  tight  .and  in  perfect  electrical  and 
mechanical  condition,  to  prevent  any  possibility  of  heating. 
The  wires  should  be  thoroughly  examined  at  regular  inter- 
vals to  see  that  the  installation  is  in  perfect  condition.  In 
fact,  inasmuch  as  there  is  always  more  or  less  (usually  more, 
and  sometimes  a  great  deal  more)  inflammable  material  con- 
stantly exposed  on  the  stage,  it  is  impossible  to  be  too  care- 


jigure  20. 


74  MOTION    PICTURE   HANDBOOK 

ful  with  the  electrical  installation  and  in  assuring  its  main- 
tenance in  perfect  condition. 

Absolutely  no  one  except  the  man  in  charge  of  the  stage 
switchboard  should  be  allowed  to  touch  it  while  a  perform- 
ance is  under  way,  and  the  fewer  persons  handling  it  at  other 
times  the  better.  Stage  switchboards  should  always  be  wired 
from  the  back.  This  is  not  absolutely  necessary,  but  it  looks 
better  and  if  better.  This  also  is  true  of  the  main  house  switch- 
board. It  is  not  necessary  that  an  expensive  marble  board 
be  purchased. 

Fixtures  such  as  those  illustrated  in  Fig.  20  may  be  had 
from  any  dealer  in  electrical  supplies.  You  may  then  pur- 
chase a  marble  or  slate  slab  of  your  local  dealer,  first  having 
ascertained  the  length  of  the  fixture  bolts  so  that  a  slab  of 
proper  thickness  may  be  selected.  Having  secured  such  a 
slab,  any  man  of  ordinary  intelligence  can  lay  out  and  drill 
the  holes.  Affixing  the  fixtures  to  the  slab  is  then  merely  a 
matter  of  placing  the  bolts  in  the  holes  and  tightening  the 
nuts. 

For  a  small  board,  one-half  inch  asbestos  millboard  makes 
a  fairly  good  support.  If  it  is  a  main)  house  switch- 
board the  sides  of  such  a  board  must  afterward  be  covered 
with  a  metal  rim  to  receive  a  metal  door.  If  rightly  done 
such  a  board  will  not  be  excessive  in  cost  and  will  look  very 
much  better  than  a  board  built  up  of  blocks  as  per  Fig.  18. 
First  lay  out  the  board  on  paper,  just  as  you  want  it,  loca- 
ting all  the  holes  carefully,  then  lay  the  paper  on  the  marble, 
slate,  or  whatever  base  you  use,  mark  the  holes,  and  drill 
them.  Manufacturers  will,  upon  request,  supply  you  with  a 
catalog  giving  the  dimensions  of  fixtures  such  as  are  shown 
in  Fig.  20. 

A  general  idea  of  the  layout  of  a  small  moving  picture 
theatre  switchboard  is  had  from  Fig.  21,  in  which  X-X-X-X, 
etc.,  are  circuit  switches,  carrying  fuses,  and  Y  and  Z  fuses 
and  switches  on  the  stage  and  operating  room  circuits. 

A  small  gas  plier  is  the  handiest  tool  with  which  to  remove 
and  insert  cartridge  fuses.  Wrap  the  handles  of  the  pliers  with 
insulating  tape  to  avoid  possibility  of  shock. 

If  a  fuse  blows  and  you  are  not  certain  which  one  it  is 
touch  your  test  lamp  terminals  to  the  fuse  terminals  before  mov- 
ing either  fuse  and  without  opening  the  switch.  If  the  lamp 
lights  that's  the  fuse.  If  it  doesn't  then  it  is  the  other  fuse. 
If  it  lights  on  neither  then  either  both  fuses  are  blown  or 
the  circuit  is  open  somewhere.  To  make  this  test  on  pro- 
jection circuit  fuses  the  carbon  must  be  frozen. 


FOR   MANAGERS   AND   OPERATORS  75 


rase. 


\          ( 


t 


Figure  21. 


76 


MOTION    PICTURE    HANDBOOK 


Fuses 

AS  has  already  been  set  forth,  an  electric  conductor  will 
only  carry  a  certain  given  number  of  amperes  of  cur- 
rent without  developing  heat.  See  Table  1,  Page  42. 
Ordinarily  only  the  quantity  of  current  consumed  by  the 
motors  and  lamps  attached  to  the  circuit  will  flow  over  the 
wires  of  the  circuit,  and  the  capacity  of  the  lamps  and  motors 
is  never  presumed  to  exceed  the  rated  capacity  of  the  wires. 
However,  many  things,  such  ,as  grounds,  short  circuits,  or  a 
rise  in  the  voltage  may  occur  to  cause  a  rush  of  current  suf- 
ficient to  overload  the  wires,  or,  in  the  case  of  rise  in  voltage, 
overload  the  apparatus  attached  thereto,  and  possibly  the 
wires  as  well.  The  fuse  is  .a  sort  of  automatic  safety  valve 
designed  to  take  care  of  just  this  sort  of  thing. 


Figure   22. 

In  Fig.  22  we  see  the  principle  of  the  fuse  illustrated.  The 
wires  of  the  circuit  are  cut  and  their  ends  attached  to  ter- 
minals A-A-A-A  fastened  to  slate  base  B.  Under  these 
terminals  are  clamped  two  pieces  of  fuse  wire  composed  of 
an  alloy  of  metals  having  very  low  melting  temperature  and 
a  high  temperature  coefficient,  which  means  that  their  re- 
sistance rises  very  rapidly  with  increased  temperature.  The 
operation  is  as  follows:  The  current  capacity  of  the  fuse 
wires  is  in  no  case  presumed  to  exceed  the  rated  capacity 
of  the  wires  of  the  circuit  they  protect  (See  Table  1)  and  to 
only  exceed  the  combined  current  consuming  capacity  of  the 
lamps  attached  to  the  circuit  by  a  small  margin,  and  to  only 
exceed  the  combined  current  consuming  capacity  of  the 
motors  by  25  per  cent. 

Assuming,  for  example,  a  circuit  the  wires  of  which  are 
rated  at  6  amperes  R.-C.,  and  that  a  sufficient  number  of  in- 
candescent lamps  are  attached  to  consume  a  total  of  5  amperes, 
we  would  insert  a  5-ampere  capacity  fuse  wire  between  the 
terminals  of  our  block,  Fig.  22.  Such  fuses  would  actually 
carry  a  little  more  than  5  amperes,  because  fuses  are  designed 


FOR    MANAGERS    AND    OPERATORS 
TABLE   No.  4 


77 


1 


HH 


T? 


«i 


0 


3  5 


llSji 

dES-aS^g 


Z  «"oj 

*ss« 


I  uuoj 


2  raj 


r 


6    § 


.     w 


ll 

c3       O, 

6 


1  IUJOJ 


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11 


888 


78  MOTION   PICTURE   HANDBOOK 

to  carry  a  10  per  cent,  overload  in  excess  of  their  rated  ca- 
pacity, in  order  to  allow  for  ordinary  fluctuations  in  voltage. 
Now  suppose  a  short  circuit  or  ground  occurred  somewhere 
on  the  circuit,  which  would  cause  a  rush  of  current  and  over- 
load the  wires,  or  suppose  there  is  a  heavy  rise  in  the  voltage, 
which  would  have  the  effect  of  forcing  more  current  through 
the  resistance  of  the  lamps,  thus  overloading  the  wires, 
with  possibility  of  results  more  or  less  disastrous.  What 
happens?  Why,  just  this:  The  fuse  wire  is  overloaded 
and  becomes  hot,  whereas  no  damage  would  be  done  to 
the  copper  wire  until  it  reached  a  temperature,  far  in 
excess  of  that  which  would  melt  the  fuse  wire,  therefore 
both  the  wires  of  the  circuit  and  the  lamps  are  pro- 
tected by  reason  of  the  fact  that  the  fuse  wire  melts  and 
automatically  stops  all  flow  of  current,  thus  "cutting  out  the 
circuit."  Nor  can  a  new  fuse  be  installed  until  the  trouble 
has  been  remedied,  since  if  an  attempt  be  made  to  install  a 
new  fuse  without  removing  the  seat  of  the  difficulty  it  would 
promptly  melt  (blow)  and  again  stop  the  flow  of  current. 
That  is  the  theory  of  the  fuse,  as  well  as  its  practical  opera- 
tion, though  raw  fuse  wire  is  not  employed  in  theatres,  except 
in  the  "link"  fuses  used  in  some  cities  to  protect  projection 
lamp  circuits,  the  same  being  located  in  an  iron  cabinet  in 
the  operating  room. 

Safety  fuses  are  made  in  a  number  of  forms,  but  those  with 
which  the  moving  picture  operator  comes  into  contact  are 
known  as  the  "plug"  or  the  "cartridge,"  both  these  forms 
being  in  general  use  in  theatres. 


Figure  23. 

In  Fig.  23,  A,  B,  are  cartridge  fuses  with  different  styles  of 
terminals,  A,  the  "ferrule"  contact,  only  being  allowed   on 


FOR  MANAGERS  AND  OPERATORS 


79 


circuits  carrying  60  amperes  or  less.     C  and  D  are  receptacles 
for  A  and  B.    B  is  the  "knife-blade"  contact  fuse. 

Cartridge  Fuses. — A  cartridge  fuse  consists  of  two  metal 
terminals  joined  by  a  paper  barrel.  Inside  this  barrel  is  the 
fuse  wire,  connecting  the  two  terminals,  with  a  small  pilot 
wire  passing  under  the  round  spot  on  the  paper  label,  as  is  il- 
lustrated in  Fig.  24.  An  air  chamber  is  used  in  some  fuses, 
the  idea  being  that  the  heat  conduction  through  the  confined 


Figure   24. 

air  being  slow,  the  temperature  in  that  part  of  the  fuse  will 
rise  rapidly  and  always  in  the  same  ratio,  thus  establishing 
a  practically  constant  point  of  blowing. 

The  fuse  wire  is  surrounded  by  a  powdered,  non-conducting 
substance  designed  to  instantly  break  the  arc  when  the  fuse 
blows.  On  the  paper  label  on  the  outside  of  the  barrel  is  a 
small  round  spot,  under  which  the  pilot  wire  passes.  When 
the  fuse  blows  the  pilot  wire  is  supposed  to  melt  and  turn  the 
spot  black,  but  it  doesn't  always  do  it. 

Table  4  gives  an  idea  of  the  essential  points  in  a  cartridge 
fuse.  The  Underwriters  require  that  the  contacts  have  a  cer- 
tain area,  that  the  paper  barrels  have  a  certain  length  and 
diameter,  and  that  the  fuses  have  a  certain  length  over  all 
for  a  given  voltage  and  amperage.  Table  4  is  taken  bodily 
from  the  "National  Electric  Code." 


80  MOTION    PICTURE    HANDBOOK 

PLUG  FUSES 

The  plug  fuse,  A,  Fig.  25,  consists  of  a  porcelain  base  with  a 
brass  screw,  and  a  center  contact  at  its  lower  end,  with  a 
protecting  brass  cap  at  its  upper  end,  the  latter  usually  hav- 
ing a  clear  mica  center  so  that  you  can  look  through  and  see 
if  the  fuse  wire  is  intact.  Ordinarily,  however,  you  cannot 
do  anything  of  the  kind  with  .any  degree  of  certainty,  any 
more  than  you  can  depend  with  certainty  on  the  spot  of  the 
cartridge  fuse  turning  black  when  the  fuse  blows.  The  only  way 


Figure  25. 

is  to  test  a  fuse  in  the  manner  set  forth  further  on.  B,  Fig.  25, 
shows  the  receptacle  for  plug  fuse  A,  and  C  a  fuse  with  the 
cap  off,  showing  fuse  wire.  D  is  a  special  form  of  plug  fuse 
to  be  used  with  amperage  between  35  and  60.  Plug  fuses,  in 
their  regular  form,  A,  Fig.  25,  are  not  made  in  excess  of  35 
amperes  capacity.  They  are  not  made  in  any  form  for  capac- 
ity in  excess  of  60  amperes.  Plug  fuses  may  be  used  for  any 
kind  of  work  up  to  the  limit  of  their  capacity.  They  are  per- 
fectly safe,  and  somewhat  cheaper  than  the  cartridge  fuse. 


LINK  FUSES 

The  link  fuse,  Fig.  26,  provided  its  receptacle  be  placed  in- 
side .a  metal  box  having  a  metal  cover,  is  perhaps  the  best 
fuse  to  use  for  the  projection  circuit;  this  for  several  reasons, 
not  the  least  important  of  which  is  the  fact  that  it  cannot 


FOR   MANAGERS    AND    OPERATORS  81 

readily  be  "boosted"  without  the  trick  being  plainly  visible 
to  the  inspector.  In  other  words,  the  link  fuse  is  very  largely 
fool-proof.  With  both  the  plug  and  cartridge  fuses  it  is  quite 
possible  for  operators  possessed  of  more  cunning  than  good 
sense  to  increase  the  capacity  of  their  fuses  almost  indefinitely 
by  placing  a  short  piece  of  copper  wire,  or  sheet  copper,  called 
a  "jumper"  in  the  terminals  in  such  manner  that  it  is  under 
the  fuse,  hence  out  of  sight.  Such  a  trick  could  only  be  de- 
tected by  close  inspection,  which  is  not  "true  of  the  link  fuse. 
The  plug  fuse  may  be  boosted  after  the  same  fashion  by 
placing  a  copper  penny  inside  the  receptacle  and  screwing 
the  plug  down  on  it  in  such  manner  that  the  two  contacts 
are  connected  by  the  copper.  Such  tricks  as  this,  however, 
render  the  fuse  of  no  value,  and  leave  the  circuit  to  all  intents  and 
purposes  entirely  unprotected.  They  cannot  be  too  strongly  con- 
demned, and  any  operator  or  other  person  caught  boosting  fuses 
ought  to  be  instantly  discharged  and  have  his  license,  if  he  have 
one,  revoked.  By  reason  of  the  difficulty  in  boosting  a  link  fuse 
the  Department  of  Water  Supply,  Gas  and  Electricity  of  the  City 
of  New  York  has  issued  a  rule  compelling  the  use  of  link  fuses 
on  projection  circuits  where  the  current  used  exceeds  the  capacity 
of  the  ordinary  plug  fuse,  viz.,  35  amperes.  Both  fuse  blocks  and 
switches  may  be  had  to  carry  link  fuses.  (See  Fig.  15.) 

Never  fuse  above  the  rated  capacity  of  the  wires  of  the  circuit. 
Never  fuse  an  incandescent  lamp  circuit  above  the  combined  am- 
perage capacity  of  its  lamps.  Never  fuse  a  motor  circuit  above 
the  rated  capacity  of  the  wires,  or  more  than  25  per  cent,  above 
the  rated  capacity  of  the  motor  or  motors. 

Underwriters'  rules  allow  the  fusing  of  the  motor  circuit  to 
25  per  cent,  above  the  capacity  of  the  motor,  or  the  combined 
capacities  of  two  or  more  motors,  provided,  of  course,  the 
wires  are  large  enough. 

It  is  physically  possible  to  refill  both  the  cartridge  and  plug 
fuse,  but  it  does  not  pay  to  do  so.  The  only  safe  rule  is : 

Throw  all  blown  fuses  away.  There  will  then  be  no  mixing 
zvith  the  good  ones,  with  consequent  vexatious  delays.  If  you 
mix  your  good  fuses  with  bad  ones  you  are  more  than  apt  to 
have  such  delays,  which  may  and  probably  will  happen  just  at 
the  very  worst  possible  time,  and  be  chargeable  entirely  to  your 
own  carelessness. 


PROJECTION  CIRCUIT  FUSES 

The  projection  circuit  offers  nothing  in  any  way  susceptible 
to  damage  through  momentary  overload.     It  is  a  nuisance  to 


82 


MOTION    PICTURE   HANDBOOK 


have  fuses  constantly  blowing,  and,  since  the  resistance  of 
the  hand-fed  arc  lamp  is  a  variable  quantity,  current  flow  will 
under  any  condition  vary  considerably.  I  would  therefore 
recommend  for  projection  circuits  the  following,  with  the 
understanding  that  the  current  flow  at  the  arc  is  what  is  re- 
ferred to  under  the  heading  "Normal  Amperage."  Of  course, 
if  the  fusing  is  only  done  on  the  primary  of  a  transformer 
(economizer,  compensarc,  inductor,  etc.)  then  due  allowance 
must  be  made. 

TABLE  NO.  5. 

Operating  room  fuse  capacity  where  rheostats  are  used  for 
resistance. 

Necessary  size  as- 

. beskos    covered 

Normal  Arc  portion  of  cir-  portion  of  cir- 

Amperage  Fuse  to  cuit   wires  cuit  wires 

20  25  6  6 


25 
30 
35 
40 

45 
50 
55 
60 


Necessary  size  R.C. 

Fuse  to 

portion  of  cir- 
cuit  wires 

25 

6 

30 

6 

35 

6 

45 

6 

55 

5 

60 

4 

75 

3 

80 

3 

85 

2 

Explanation  of  Table  5 :  Wires  must  be  large  enough  to  ac- 
commodate the  fuse  capacity  without  overload.  That  portion  of 
the  circuit  which  is  asbestos-covered  wire  may  be  treated  as 
weather-proof  in  this  respect. 

FUSING  FOR  MOTOR  GENERATOR  OR  ROTARY 
CONVERTER 

This  is  a  simple  matter.  Ordinarily  there  are  fuses  both 
on  the  intake  and  output  lines — on  the  motor  and  generator 
side.  Ascertain  the  amperage  at  your  arc  under  normal  con- 
ditions, and  add  about  20  per  cent,  of  that  amount,  which  will 
give  the  size  for  your  fuses  on  the  generator  or  output  side. 
The  arc  will,  of  course,  be  D.  C.,  hence  48  volts.  Therefore 
the  arc  amperage  multiplied  by  48  will  give  the  arc  wattage, 
which,  divided  by  the  intake  (line)  voltage,  will  give  the  in- 
take amperage,  or  would  give  it  if  the  machine  had  100  per 
cent,  efficiency.  Few  machines,  however,  have  more  than  65 
per  cent,  efficiency;  therefore  to  this  must  be  added  35  per 
cent,  in  order  to  get  the  actual  intake  in  amperage,  thus: 
Assuming  a  line  voltage  of  110  and  an  arc  wattage  of  1920, 
then  1920  watts  -^-  110  volts  =  \7l/2  amperes,  and  35  per  cent, 
of  \7l/2  amperes  is  6l/2  amperes  and  \7l/2  +  6l/2  =  24,  therefore 
the  intake  amperage,  based  on  the  assumption  that  the 


FOR   MANAGERS   AND   OPERATORS  83 

machine  has  65  per  cent,  efficiency,  is  24,  but  we  will  install 
30  ampere  fuses,  since  the  Underwriters  approve  of  fusing 
a  motor  25  per  cent,  above  its  actual  capacity. 

The  following  must  be  qualified,  however,  by  the  fact  that 
if  the  generator  is  of  higher  voltage  than  the  arc,  then  the 
arc  amperage  must  be  multiplied  by  the  voltage  of  the 
generator  instead  of  the  voltage  of  the  arc,  since  resistance 
will  have  to  be  used  to  cut  down  the  voltage  to  48,  and  vol- 
tage wasted  in  resistance  counts  just  the  same  as  that  used 
in  operating  the  arc. 

Plenty  of  fuses  should  be  kept  on  hand.  You  never  can  tell 
when  one  -will  blow,  and  sometimes  a  sort  of  epidemic  of  fuse 
blowing  occurs.  It  is  very  awkward  to  get  caught  without  fuses, 
and  the  only  insurance  against  it  is  a  good  surplus  stock,  but  be 
very  careful  that  blown  fuses  don't  get  mixed  with  the  good  ones. 

In  case  you  do  get  caught  without  fuses  you  can  protect  the 
circuit  temporarily  with  one  fuse,  bridging  the  two  other  fuse 
terminals  with  copper  wire.  This  is  by  no  means  a  good  con- 
dition, and  may  only  be  tolerated  temporarily,  in  case  of  emer- 
gency, until  the  proper  fuses  can  be  procured.  Such  a  condition 
would,  in  fact,  be  very  bad,  and  emergencies  of  this  kind  never 
ought  to  occur.  It  is  possible  to  make  a  fuse  of  copper  wire, 
and  while  such  a  fuse  would  be  to  a  considerable  extent  unre- 
liable, and  from  every  point  of  view  objectionable,  still  it  may  be 
used  temporarily  in  an  emergency,  therefore  I  give  the  fusing 
point  of  small  copper  wires. 

TABLE  NO.  6. 

Fusing  Point  of  Copper  Wires. 

American  (B.  &  S.)  Wire  Gauge     Fusing  Current  in  Amperes 

30  10 

28  15 

26  20 

25  25 

24  30 

22  40 

21  50 

20  60 

19  70 

18  80 

17  100 

16  120 

1"  140 

14  160 

13  200 


84 


MOTION    PICTURE    HANDBOOK 


By  adding  two  copper  wires  of  different  sizes  together, 
fuses  of  almost  any  desired  strength  may  be  had,  thus:  A 
No.  30  and  17  wire  combined  would  make  a  47  ampere  fuse. 


IN  CASE  OF  TROUBLE 

Should  a  fuse  blow  and  upon  installing  a  new  one  it  also 
immediately  blows,  it  is  conclusive  proof  there  is  heavy  over- 
load, most  likely  due  to  a  heavy  short  or  ground,  and  the 
circuit  must  be  left  dead  until  the  trouble  is  remedied.  You 
will  most  likely  find  the  difficulty  exists  in  the  form  of  a 
ground,  or  a  short  caused  by  something  of  current  carrying 
capacity  connecting  the  wires  at  some  exposed  point.  A 
ground,  will,  however,  be  the  most  likely  cause  of  the  trouble. 
(See  Testing  for  Grounds.) 

A  rise  in  voltage  will  operate  to  force  more  current 
through  the  lamps  and  motors,  thus  causing  an  increase  in  the 
amperage,  which  may  blow  the  fuses.  It  will  be  evidenced 
by  the  incandescent  lamps  burning  above  c.p.  Should  a  fuse 
blow  and  the  new  one  installed  also  blow  after  a  few  min- 
utes, or  an  extended  time,  first  of  all  examine  the  fuse  contacts, 
as  loose  or  dirty  contacts  will  generate  heat  which  may  be  suf- 
ficient to  cause  the  trouble. 

Fuses  will  sometimes  blow  and  it  will  be  difficult  to  tell 
which  one  of  the  two  it  is.  I  would  recommend  the  installa- 
tion at  some  convenient  point  to  the  main  switchboard  of  a 
fuse  tester  made  as  per  Fig.  27. 


Figure  27. 


FOR    MANAGERS    AND    OPERATORS  85 

A  and  B,  Fig.  27,  are  wires  of  any  circuit  that  is  always 
"alive,"  preferably  the  main  theatre  feeders  ahead  of  the 
switchboard  fuses.  If  you  attach  at  that  point  and  the  house 
is  fed  by  a  three-wire  system,  be  sure  to  attach  to  one  out- 
side wire  and  the  central  or  neutral  wire,  else  you  will  have 
220  volts  on  your  tester;  D  is  an  ordinary  cartridge  recep- 
tacle; E  a  plug  fuse  receptacle;  C  an  incandescent  lamp  of 
the  voltage  of  your  current.  When  you  put  a  fuse  in  either 
of  the  receptacles  and  lamp  C  does  not  light  the  fuse  is 
worthless  and  should  be  thrown  away. 

Cartridge  fuse  voltage  and  amperage  rating  are  usually  found 
on  a  paper  label  on  their  barrel;  the  plug  fuses  .have  their 
rating  stamped  on  the  brass  cap,  and  link  fuses  have  or 
should  have  their  rating  stamped  on  one  of  the  copper  con- 
tacts at  their  ends. 

Fuses  are  Ordinarily  Installed  as  Follows:  (a)  Main  ser- 
vice fuses,  located  ahead  (on  the  street  side)  of  the  main 
switch.  These  fuses  carry  the  entire  load  of  the  theatre,  ex- 
cept the  exit  and  other  lights  ordinarily  left  burning  during 
the  performance.  Circuits  carrying  these  latter,  called  emer- 
gency lights,  should  be  attached  to  the  feed  wires  ahead  (on 
the  street  side)  of  everything  else,  and  have  service  fuses  of 
their  own  (see  Page  86).  In  some  houses  the  stage  is  fed 
by  a  separate  set  of  feeders  coming  from  the  street  mains,  in 
which  case  these  circuits  will,  of  course,  have  main  fuses  of 
their  own.  (b)  Fuses,  usually  on  the  main  house  switchboard, 
carrying  the  operating  room  feeder  circuit,  (c)  Fuses,  on 
the  main  switchboard,  carrying  feed  wires  for  the  stage,  if 
the  stage  takes  its  current  through  the  main  switchboard,  as 
is  usually  the  case,  (d)  Main  fuses  in  the  operating  room, 
which  carry  all  operating  room  circuits.  Also  individual  ser- 
vice fuses  in  each  separate  projection  machine  line  and  oper- 
ating room  motor  and  incandescent  circuit,  (e)  Fuses,  or- 
dinarily located  on  the  main  house  switchboard,  on  each  in- 
dividual incandescent  circuit,  (f)  Fuses  on  the  stage  switch- 
board for  each  individual  circuit,  as  well  as  main  fuses  carry- 
ing all  circuits  except  exit  and  emergency  light  circuits, 
(g)  Fuses,  usually  located  in  the  box  office,  carrying  the  en- 
tire emergency  light  system,  as  well  as  fuses  for  each  in- 
dividual emergency  light  circuit,  (h)  Fuses  for  each  individual 
emergency  light,  particularly  in  the  case  of  exit  lights, 
(i)  Fuses  must  be  installed  wherever  a  change  in  size  (diameter) 
of  wire  occurs. 


86  MOTION    PICTURE   HANDBOOK 

FUSING  EMERGENCY  LIGHT  CIRCUITS 

Main  fuses  for  emergency  light  circuits  should  not  be  lo- 
cated on  the  house  switchboard,  but  should  be  in  the  box 
office.  In  addition  to  this,  every  separate  circuit  must  have 
fuses  of  its  own,  and,  still  in  addition  to  this,  it  is  an  excel- 
lent scheme  to  fuse  each  individual  emergency  light,  es- 
pecially the  exit  sign  lamps,  with  1  ampere  fuses  of  its  own, 
then  if  trouble  should  develop  in  a  lamp,  it  will  simply  blow 
its  own  fuse  without  disturbing  the  other  emergency  lights,  where- 
as otherwise  it  would,  or  at  least  might  put  out  of  commission  the 
whole  circuit,  or  possibly  even  the  entire  emergency  light  system. 

Every  circuit,  no  matter  how  large  or  how  small  it  may  be, 
must  be  protected  by  its  own  individual  fuses,  in  addition  to  the 
main  fuses  carrying  all  circuits. 

Plug  or  cartridge  fuses  are  the  only  types  it  is  permissible 
to  use  in  a  theatre,  except  that,  unless  local  law  prevents, 
link  fuses  inclosed  in  metal  cabinet  may  be  used  in  operating 
rooms  for  projection  circuits. 


Figure  28. 


The  blowing  of  projection  circuit  fuses  is  a  very  annoying 
thing,  since  it  stops  the  show  and  causes  delay  while  new 
ones  are  installed.  It  does  not  necessarily  follow  there  is 
anything  wrong  because  a  projection  circuit  fuse  blows, 
particularly  if  the  circuit  is  not  fused  much  above  the  am- 
perage being  used.  By  installing  two  sets  of  projection  cir- 
cuit fuses,  as  per  Fig.  28,  delays  of  this  kind  are  avoided,  be- 
cause one  only  has  to  throw  over  the  switch  to  cut  a  new 
set  of  fuses,  and  unless  there  be  something  wrong  with  the 
circuit  there  is  no  appreciable  delay. 


FOR   MANAGERS   AND   OPERATORS 


87 


LAMPHOUSE  AND   RHEOSTAT  WIRE  TERMINALS 

Both  the  lamphouse  and  rheostat  terminals  are  subjected  to 
considerable  heat,  therefore  it  is  not  practical  to  solder  the 
lugs  to  the  wire.  There  are  a  number  of  fairly  good  termi- 
nals made  for  use  under  such  conditions,  but  those  made  to 
connect  with  the  wire  by  bending  over  and  squeezing  down 
a  set  of  copper  lips,  D-D-D,  Fig.  29,  are,  as  a  general  propo- 
sition, too  light  for  use  with  the  modern  high  amperage. 
The  best  non-solder  terminals  are  those  made  of  brass,  or 
some  composition  metal,  which  have  ample  cross-section,  and 
which  clamp  the  wire  either  by  tightening  down  on  screws 
or  by  screwing  up  a  section  of  the  terminal.  Among  the  best 
of  these  are  those  illustrated  at  A-A-A,  B-C-C-C  and  E-E, 
Fig.  29,  A-A-A  and  E-E  being  identical,  except  for  the  hook 
connection  on  the  former. 


Figure  29. 

There    are    many    other    good    lugs,    these    illustrated    being 
merely  examples. 

It  is  particularly  necessary  that  the  binding  posts  and  ter- 
minals of  the  rheostat  and  arc  lamp  be  kept  perfectly  clean, 
and,  by  reason  of  the  fact  that  metal  is  likely  to  oxidize 
under  the  action  of  heat,  both  the  rheostat  and  arc  lamp 
connections  should  be  taken  apart  about  once  a  week  and 
thoroughly  cleaned,  either  by  sandpapering  or  scraping. 
The  operator  should  not  neglect  things  of  this  kind.  He 
may  think  they  are  of  minor  importance,  but  in  that  he  is 
mistaken.  It  not  only  costs  actual  money  through  waste  of 
power,  but,  also,  by  decreasing  the  arc  amperage,  injures  the 
illumination  of  the  screen. 


88  MOTION    PICTURE    HANDBOOK 


Wire  Terminals 


EVERY  wire  ought  to  have  a  terminal  lug,  and;  except 
in  cases  where  the  same  will  be  subjected  to  heat,  as, 
for  instance,  in  a  lamphouse  or  on  a  rheostat,  these 
lugs  should  be  soldered  to  the  wire.  They  come  in  a  num- 
ber of  forms,  but  almost  any  of  them  will  serve  the  purpose 
very  well  if  properly  attached  to  the  wire.  In  order  to 
solder  a  lug  to  the  wire  proceed  as  follows:  First  measure 
the  depth  of  socket  in  the  lug,  and  cut  off  enough  of  the 
insulation  of  the  wire  to  just  let  the  end  of  the  wire  reach  the 
bottom,  scraping  the  bare  end  of  the  wire  perfectly  clean, 
until  it  shines.  This  latter  is  important,  since  otherwise  the 
wire  cannot  make  perfect  electrical  contact  with  the  solder. 
Next,  first  having  made  sure  the  inside  of  the  wire  socket  is 
perfectly  clean,  hold  the  lug  in  the  flame  of  .a  blow-torch  or 
some  other  source  of  heat  and  melt  sufficient  solder  into  it 
to  fill  the  hole  .about  half  full.  Don't  get  the  terminal  too 
hot,  but  just  hot  enough  to  make  the  solder  thoroughly 
liiquid.  Now,  having  put  a  little  flux  on  the  bare  part  of  the 
wire,  shove  it  down  into  the  solder  and  hold  it  until  it  sets. 

Caution.— Don't  shove  the  wire  into  the  lug  with  a  quick 
push.  If  you  do  the  solder  will  probably  squirt  out,  and  you 
may  get  badly  burned.  Warm  the  end  of  the  wire  and  then 
shove  it  in  firmly,  but  not  too  fast.  If  directions  are  fol- 
lowed you  will  have  a  perfect  electrical  joint.  In  attaching 
terminal  lugs  to  binding  posts  always  be  sure  that  both  the 
lug  and  binding  post  are  perfectly  clean.  A  little  No.  0  sand- 
paper or  emery  cloth  will  be  found  handy  for  cleaning  con- 
tacts; also  you  can  scrape  them  with  a  knife  blade..  It  is, 
however,  exceedingly  important  that  when  a  copper  wire  is 
joined  directly  to  a  -binding  post  it  be  perfectly  clean,  since 
ofttimes  a  thin  coating  of  oxidation  will  cover  the  metal, 
and  this  coating,  while  it  is  almost  thin  enough  to  be  in- 
visible, offers  high  resistance.  The  resistance  of  one  such 
joint  would  not  amount  to  very  much,  but  that  of  a  dozen 
would  cost  you  a  good  many  dollars  in  wasted  energy  in  the 
course  of  the  year — remember  that  your  meter  registers  all 
energy  consumed,  whether  it  be  used  in  overcoming  useless 
resistance  or  in  the  production  of  light  and  power. 


FOR    MANAGERS    AND    OPERATORS 
WIRE  SPLICES 


89 


A  wire  splice  is  something  every  operator  should  know  how 
to  make  correctly.  An  imperfect  splice  will  heat  and  cause  loss 
of  power.  It  may  cause  the  wire  to  burn  off  entirely.  In  any 
event  it  is  a  constant  source  of  loss  of  energy  through  its  ex- 
cessive resistance. 

A  splice  must  be  electrically  perfect,  and  should  in  all  cases, 
unless  a  strictly  temporary  joint,  be  soldered. 

In  Fig.  30  several  correct  methods  of  making  splices  are 
illustrated.  First,  the  insulation  must  be  removed  from  the 
two  ends  to  be  joined,  for  a  distance  of  from  two  to  four 
inches,  according  to  size  of  the  wire.  The  insulation  should 
be  whittled  away  just  as  you  whittle  a  lead  pencil.  Never 
cut  the  insulation  square  off  by  running  the  knife  blade 
around  the  wire.  This  makes  a  very  neat  looking  job,  but 
the  trouble  is  that  the  blade  is  likely  to  cut  a  slight  ring 
around  the  wire,  and  this  ring  acts  very  much  as  a  scratch 


Figure  30. 

on  the  surface  of  glass  does,  causing  the  wire  to  break  very 
easily  at  that  point.  The  correct  method  is  shown  at  A, 
Fig.  30,  and  the  incorrect  at  B.  What  is  perhaps  the  best 
method  of  making  a  splice  in  asbestos  covered,  stranded  wire 
is  illustrated  at  C,  Fig.  30,  except  that  the  strands  should  be 
divided  into  about  six  sections. 

After  removing  the  insulation  the  wire  ends  must  be  thor- 
oughly cleaned,  until  they  shine.  This  may  be  done  with 
emery  paper,  or  by  scraping  with  a  knife  blade.  But,  however 
it  is  done,  the  wire  must  be  made  perfectly  clean,  else  there 
will  not  be  good  electrical  contact.  The  wire  ends  must 


90  MOTION    PICTURE   HANDBOOK 

then  be  twisted  tightly  together  as  at  1,  Fig.  30,  after  which 
the  joint  must  be  soldered.  Underwriters'  rules  provide  that 
a  wire  splice  must  be  made  both  mechanically  and  electrically 
perfect  before  soldering.  After  the  joint  is  made,  as  per 
Fig.  30,  proceed  to  solder  it  as  follows:  Wet  it  thoroughly 
with  a  soldering  fluid,  or  its  equivalent,  which  may  be  had 
from  electrical  dealers  in  stick  form.  An  excellent  soldering 
fluid  is  made  of 

Saturated  solution  of  zinc  chloride 5  parts. 

Alcohol 4  parts. 

Glycerine    1  part. 

After  thoroughly  wetting  the  joint  with  the  fluid,  or  rubbing 
on  plenty  of  the  flux  in  stick  form,  hold  the  wire  in  the  blaze 
of  a  gasoline  torch  until  warm,  and  then  also  hold  in  the 
blaze  a  piece  ,of  solder,  which  may  be  had  of  electrical  deal- 
ers in  wire  form,  until  it  melts  and  runs  all  through  the  joint. 
Care  must  be  had  not  to  get  the  wire  too  hot,  ~ince,  especially 
with  the  smaller  wires,  too  much  heat  causes  injury  and 
reduces  the  carrying  capacity;  also  if  too  hot  the  solder  will 
run  through  and  out  of  the  joint.  If  the  soldering  is  proper- 
ly done  the  joint  will  have  more  mechanical  strength  and  as 
great  carrying  capacity  as  the  wire  itself.  All  joints  must  be 
soldered,  except  they  be  strictly  temporary,  say  to  use  for  one 
day  only.  After  soldering,  the  splice  must  be  wrapped  with 
insulating  tape,  to  the  depth 'of  the  original  insulation.  One 
or  two  thicknesses  of  tape  are  not  enough.  If  properly  done, 
the  use  of  a  wire  connector,  D,  Fig.  30,  is  permissible;  but 
the  soldered  joint  is  best.  Wire  connectors  must  not  be  used 
for  joining  asbestos-covered,  stranded  wires,  except  the  end 
of  the  wire  be  first  run  full  of  solder,  thus  binding  the 
strands  together  in  a  solid  mass. 

For  wires  connecting  to  switch,  or  other  cold  binding  posts, 
lugs  similar  to  E,  F,  G,  Fig.  30,  must  be  used,  but  before  in- 
serting wire  ends  into  connectors,  or  lugs,  they  must  be  thor- 
oughly cleaned  by  scraping  with  a  knife  blade,  or  polishing 
with  emery  paper.  Where  such  lugs  are  used,  the  wire  must 
be  soldered  into  them. 

Keep  always  in  mind  the  fact  that  unless  a  wire  splice  or 
joint  be  very  carefully  made  it  will  heat  more  or  less  and 
cause  resistance,  which  means  constant  loss  as  long  as  the 
splice  or  joint  is  used.  The  loss  from  one  imperfect  splice 
or  joint  may  be  slight,  but  the  combined  loss  from  several 
may  amount  to  considerable. 


FOR   MANAGERS   AND   OPERATORS  91 


Lenses 


BROADLY  speaking,  the  function  of  a  lens  is  to  receive 
upon  every  portion  of  its  surface  light  rays  emanating 
from  every  pinpoint  of  the  surface  of  a  more  or  less 
distant  object,  and  to  so  reflect  and  direct  these  rays  that 
the  image  of  the  object  will  be  formed,  either  of  equal,  less, 
or  greater  dimensions  than  those  of  the  original  object,  at 
a  distance  from  the  opposite  side. 

There  are  many  terms  used  in  connection  with  lenses,  but 
I  think  that,  so  far  as  the  operator  be  concerned,  only  a  few 
are  of  real  importance. 

The  Optical  Axis  of  the  lens  is  an  imaginary  line  running 
exactly  through  the  center  of  the  diameter  of  the  lens,  or,  in 
other  words,  the  center  of  the  lens,  being  precisely  at 
right  angles  to  its  plane.  Another  way  of  expressing  it 
would  be  that,  understanding  that  the  surface  of  a  lens  is 
always  the  surface  of  a  segment  of  a  true  sphere,  a  line  drawn 
from  the  exact  center  of  the  circles  shown  in  Fig.  34 
through  the  exact  center  of  either  one  of  the  two  lenses 
shown  would  of  necessity  be  the  optical  axis  of  the  lens, 
because  it  would  pass  exactly  through  the  center  of  the 
lens  and  be  exactly  at  right  angles  to  its  plane. 

The  Conjugate  Foci  refers  to  two  points,  one  being  the 
distance  to  the  lens  from  a  light  source  or  object,  and  the 
other  to  the  distance  from  the  lens  to  the  point  where  the 
rays  from  the  light  source,  or  object,  are  refocused  into  an 
image.  Altering  the  distance  of  one  of  these  points  from 
the  lens  automatically  alters  the  other. 

The  conjugate  foci  are  shown  in  Fig.  32,  in  which  the 
object  might  be  substituted  for  the  image,  without  changing 
the  general  effect.  The  image  would  occupy  the  position  now 
occupied  by  the  object  and  vice  versa.  In  a  projection  ma- 
chine the  conjugate  foci  points  of  its  objective  lens  are  the 
film  at  the  aperture  and  the  screen.  If  an  actual  picture 
be  placed  on  the  screen  and  brightly  illuminated  and  a  piece 
of  ground  glass  be  placed  over  the  machine  aperture  it  would 
be  found  that  an  image  of  the  picture  would  appear  thereon, 
and  if  the  picture  be  the  size  ordinarily  projected  by  the 
lens  at  that  distance,  then  the  image  will  just  fill  the  machine 
aperture. 


92  MOTION    PICTURE    HANDBOOK 

Refraction. — A  lens  depends  for  its  action  on  the  fact  that 
light  rays  traveling  through  a  transparent  medium  of  uni- 
form density  will  travel  in  straight  lines  until  they  enter,  at 
an  angle,  a  transparent  medium  of  different  density,  where- 
upon, at  the  exact  point  of  entry  into  the  second  medium, 
their  direction  will  be  changed  and  the  amount  of  change 
will  be  in  proportion  to  (a)  the  angle  at  which  the  ray  enters 
the  second  medium  and  (b)  the  relative  density  of  the  second 
medium  as  compared  with  the  first.  If  the  angle  at  which  the 
rays  strike  the  second  medium  be  slight  the  bending  or 
refraction  will  be  slight;  if  the  angle  be  .heavy  the  bending 
(refraction)  will  be  proportionately  greater.  If  the  differ- 
ence in  density  of  the  two  mediums  be  slight  the  bending 
(refraction),  due  to  this  fact,  will  be  slight;  if  the  difference 
in  density  be  great,  then  the  bending  of  the  rays  will  be  pro- 
portionately greater. 

It  is  somewhat  difficult  to  intelligently  explain  the  reason 
for  the  bending  of  the  light  ray,  nor  do  I  know  that  from 
the  operator's  viewpoint  it  is  necessary.  Suffice  it  to  say  that 
light  rays  do  bend  under  the  conditions  before  named;  there- 
fore, when  light  passes  from  air  into  glass  at  an  angle  or 
from  glass  into  air  at  an  angle,  the  ray  is  bent  (refracted) 
and,  as  before  said,  the  amount  of  bending  will  depend  upon 
the  amount  of  angle  and  the  relative  density  or  refractive 
index  of  the  glass  as  compared  to  that  of  the  surrounding 
air.  The  refractive  index  of  glass  is  equal  to  the  size  of  the 
angle  made  by  the  incident  ray,  divided  by  the  size  of  the 
angle  made  by  the  refracted  ray. 

In  this  connection  it  would  be  interesting  to  know  whether 
there  would  be  any  actual  difference  as  between  the  action 
of  a  lens  used  at  sea  level  and  one  used  at,  say,  the  summit  of 
Pike's  Peak.  Theoretically  there  would;  practically,  I  doubt 
it.  It  is  merely  an  interesting  point,  based  on  the  fact  that 
the  amount  of  refraction  depends  partly  upon  the  relative 
density  of  the  two  mediums. 

Back  Focus. —  The  "back  focus"  of  a  lens  (commonly  ex- 
pressed as  B.  F.)  is  the  distance  from  the  object  (film  in  the 
case  of  the  projector  objective)  to  the  first  surface  of  the 
lens.  This  is  a  very  important  matter  to  the  operator,  since 
it  is  practically  impossible  for  him  to  locate  the  point  of 
equivalent  focus  (E.  F.)  in  any  given  objective  with  accuracy; 
also  it  would  be  very  difficult  for  the  operator  to  measure 
the  actual  distance  from  the  point  of  E.  F.  to  the  film  with 
the  lens  in  actual  working  position,  and,  since  any  given  lens 
may  work  in  a  great  many  different  positions  (distance  from 


FOR   MANAGERS    AND    OPERATORS  93 

the  film),  and  these  different  positions  of  the  objective  re- 
quire special  treatment  in  the  matter  of  the  condenser,  it  is 
highly  important  that  the  operator  be  able  to  make  precise 
measurement  of  the  lens  position.  This  is  made  possible  by 
using  the  back  focus  for  the  purpose,  only  using  the  E.  F. 
to  figure  focal  length  of  lens  necessary  to  project  a  picture 
of  given  size  at  a  given  distance. 

Equivalent  Focus. — "Equivalent  focus"  is  a  term  applied  to 
lenses  made  up  of  two  or  more  lenses,  as  the  objective  lens. 
It  simply  means  that  the  combination  will  possess  the  same 
power  of  reduction  or  magnification  possessed  by  a  single, 
simple  lens  of  equal  focus.  For  example:  if  your  objective 
is  a  4J^  inch  E.  F.,  then  it  will,  working  under  the  same  con- 
dition, project  the  same  size  picture  that  a  single  lens  of  4J^ 
inch  focus  would  project,  the  difference  being  that  the  single 
lens  would  not  project  nearly  so  good  an  image.  Equivalent 
focus  is  of  value  to  the  operator  for  one  thing,  and  one 
thing  only,  viz:  in  computing  the  focal  length  lens  required 
to  project  a  picture  of  given  size  at  a  given  distance. 

In  order  to  understand  lens  action  it  is  necessary  to  get 
the  "viewpoint,"  and  that  is  a  very  difficult  thing  to  impart  to 
the  student.  Each  infinitesimal  pinpoint  on  the  surface  of 
a  lens  is,  from  an  optical  standpoint,  an  entirely  separate 
proposition  from  every  other  infinitestimal  portion  of  the 
surface  of  that  lens,  since,  because  of  the  fact  that  a  lens 
has  curvature,  each  pinpoint  of  surface  offers  a  different 
angle  to  the  light,  and  therefore  gives  a  refraction  slightly  dif- 
ferent from  that  of  the  pinpoint  next  adjoining  it,  and  a  dif- 
ferent retraction  from  that  of  all  other  points  on  its  surface  as 
well. 

Remembering  that  the  amount  of  refraction  a  light  ray  will 
receive  upon  passing  from  air  to  glass,  or  vice  versa,  will 
depend  to  a  very  large  extent  upon  the  angle  at  which  the 
ray  strikes  the  glass  in  entering,  or  strikes  the  air  in  leaving, 
and  the  further  fact  that,  having  entered  the  lens  and  re- 
ceived its  refraction  at  the  point  of  entry,  the  ray  will  travel 
(provided  the  glass  be  of  even  density,  as  it  must  be  in  a 
good  lens)  in  a  perfectly  straight  line  until  it.  strikes  the 
other  surface  of  the  glass  and  re-enters  the  air,  where  it  is 
again  refracted,  it  will  readily  be  seen  that  the  entire  refrac- 
tion takes  place  at  the  point  of  entry  and  exit.  It  therefore 
follows  that  the  refractive  power  of  a  lens  depends  entirely 
upon  its  surfaces,  and  that  the  glass  underneath  is  of  no 
value  whatever,  so  far  as  refraction  be  concerned,  except  to 
act  as  a  support  for  the  surfaces.  In  fact  in  condensing 


94  MOTION   PICTURE   HANDBOOK 

lenses  the  glass  is  a  distinct  detriment,  in  that  it  absorbs 
light  in  proportion  to  its  thickness,  but  this  is  a  necessary 
evil,  since  in  order  to  accomplish  a  certain  degree  of  refrac- 
tion a  lens  must  have  a  certain  degree  of  curvature,  and  that 

curvature  compels  the 
use  of  a  fixed  amount 
of  glass  to  act  as  its 
support. 

This  statement,  how- 
ever, must  be  qualified 
when  it  is  applied  to  the 
Figure  31.  objective     lens,     where 

combinations  of  crown 

and  flint  glass  are  used  to  correct  faults.  For  instance :  the  front 
wide  lens  of  an  objective  is  very  thick — often  as  much  as  three- 
eighths  of  an  inch  of  glass  being  used,  although  the  surfaces 
could  be  carried  in  their  relation  to  each  other  by  a  far  less 
amount.  I  assume,  however,  that  this  thickness  is  due  to  the 
fact  that  it  is  necessary  to  have  a  certain  amount  of  flint 
glass  in  proportion  to  the  amount  of  crown  glass  used,  in 
order  to  fully  correct  chromatic  aberr.ation. 

Spherical  Aberration. — Spherical  aberration  is  that  quality 
of  a  lens  which  produces  an  uneven  refraction  or  bending 
of  the  light  rays  at  different  portions  of  the  lens.  Rays 
passing  through  the  outer  edge  of  an  uncorrected  lens  will 
be  refracted  or  bent  to 
such  an  extent  that  they 
will  refocus  at  a  point 
considerably  nearer  the 
opposite  face  of  the  lens 
than  will  those  rays  pass- 
ing through  nearer  the 
center  or  optical  axis  of 
the  lens.  (See  Fig.  31.)  Figure  32 

The  effect  of  spherical 

aberration  on  moving  picture  projection  is  not  as  yet  thoroughly 
determined.  It  forms  an  interesting  topic  for  future  study. 
Spherical  aberration  is  overcome  or  corrected  by  combining  a 
concave  lens  with  one  having  convex  surfaces.  These  lenses 
must  be  so  proportioned  that  the  excessive  converging  powers 
of  the  outer  surface  of  the  lens  is  just  counterbalanced  by  the 
diverging  effect  of  the  concave  lens.  (See  Page  98.) 

Chromatic  Aberration. — Chromatic  aberration  is  that  qual- 
ity of  a  lens  which  causes  it  to  separate  white  light  to  a 


FOR  MANAGERS  AND  OPERATORS 


greater  or  less  extent  into  its  primary  colors.  Chromatic 
aberration  may  be  corrected  or  eliminated  by  a  combination 
of  flint  and  crown  glass. 

The  objective  lens  is  corrected  for  both  spherical  and 
chromatic  aberration,  and  that  is  the  reason  for  the  four 
lenses  and  their  different  shapes.  The  form  of  the  lenses 
corrects  spherical  aberration  and  their  composition  corrects 
chromatic  aberration. 

Now,  assuming  the  lens  in  Fig.  32  -to  be  free  from  spher- 
ical aberration,  all  the  rays  emanating  from  any  point  on 
light  source  X  and  striking  the  surface  of  the  lens  will  be 
refracted  in  such  manner  that  they  will  meet  again  at  point 
Y,  these  two  points  being  called  the  "conjugate  foci"  of  the 

lens.  If  light  source  X 
be  advanced  nearer  the 
surface  of  the  lens,  point 
Y,  at  which  the  rays  meet 
again,  will  be  automatic- 
ally moved  further  away 
from  the  lens,  and  if 
point  X,  the  light  source, 
be  brought  near  enough 
to  the  lens,  point  X  final- 
ly will  be  lost,  and  rays 
will  emanate  from  the 
lens  in  parallel,  or  even 
in  diverging  lines.  On 
the  other  hand,  if  light 
source  X  be  moved 
back  further  from  the 

lens,  point  Y  will  be  brought  closer  to  its  surface.  In  this 
connection  a  point  of  much  importance  in  projection  is  the 
fact  that,  while  the  foregoing  is  strictly  true  when  the  light 
source  is  a  pinpoint,  it  is  subject  to  complications  and 
modification  in  practice,  because  with  a  light  source,  say 
three-eighths  inch  in  diameter,  the  rays  emanating  from  a 
given  point  on  one  side  of  the  crater  will  strike  a  given  point 
on  the  lens  at  a  different  angle  than  will  rays  emanating  from 
a  given  point  on  the  opposite  diameter  of  the  crater.  Just 
what  and  how  much  practical  effect  this  has  on  projection  I 
do  not  know,  but  certainly  it  has  some,  and  forms  an  inter- 
esting topic  for  study.  For  one  thing  the  large  light  source 
serves  to  secure  a  reasonably  even  illumination  of  the  film 
picture,  which  would,  due  to  spherical  aberration  in  the  con- 
denser, be  impossible  with  a  very  small  crater. 


Figure  33. 


96 


MOTION    PICTURE    HANDBOOK 


At  A,  Fig.  33,  we  see  a  "long  focal"  length  lens,  which 
means  one  having  slight  curvature.  Its  refractive  powers  are 
not  so  great  as  the  lens  shown  at  B,  Fig.  33,  so  that  when 
light  source  X  is 
at  the  point  where 
X  and  Y  are  equi- 
distant from  the 
lens,  as  at  A,  and 
light  source  X  and 
the  lens  are  in  the 
same  relative  posi- 
tion at  B,  point  Y 
is  much  nearer  the 
lens.  The  lens 
shown  at  A  is  a 
"long  focal  length" 
lens,  and  the  one 
shown  at  B  a  "short 
focal  length"  lens, 
therefore  you  will 
observe  that  the  Figure  34. 

heavier  the  curva- 
ture of  the  glass  the  shorter  the  focal  length  of  the  lens   (the 
refractive  index  being  equal) ;  this  by  reason  of  the  fact  that 

the  heavier  the  curva- 
ture the  greater  will  be 
the  angle  at  which  the 
light  rays  strike  the 
glass,  hence  the  greater 
the  amount  of  its  re- 
fraction, and  the  nearer 
to  the  lens  they  will 
focus. 

The  surface  of  lenses 
used  for  projection 
work  is  always  a  sec- 
tion of  the  surface  of 
a  true  sphere.  In  Fig. 
34  we  see  how  the  cur- 
vature of  an  ordinary 
Figure  35.  plano-convex  lens  is  de- 

termined.   Assuming  the 

outer  circle  to  represent  a  glass  ball  ly?.  inches  in  diameter,  if 
you  scribe  on  its  surface  a  circle  4l/2  inches  in  diameter  and 
then  saw  off  the  section  so  outlined  and  polish  its  flat  side,  you 


FOR    MANAGERS    AND    OPERATORS  97 

would  have  a  7^2-inch  plano-convex  lens.  If  the  glass  ball  repre- 
sented by  the  inner  circle  was  6l/2  inches  in  diameter,  then  a 
similar  operation  on  the  surface  of  that  ball  would  produce  a 
6^2-inch  plano-convex  lens.  But  a  lens  may  have  two  curved 
surfaces,  as,  for  instance,  a  meniscus,  and  the  method  of  deter- 
mining these  surfaces  is  shown  in  Fig.  35,  in  which  the  two 
circles  are  made  of  a  size  to  produce  two  surfaces  which  will  give 
the  effect  desired,  section  X  representing  the  resultant  lens, 
which  will  have  a  convex  surface  on  one  side  and  a  concave 
on  the  other.  This  is  what  is  known  as  a  "meniscus"  lens. 
Its  convex  side  is  the  "positive"  and  its  concave  side  the 
"negative."  In  the  lenses  dealt  with  in  Fig.  34,  the  inner 
or  6^2-inch  lens  would  be  6^-inch  lens  because  it  would 
focus  parallel  rays  of  light  at  a  point  6^  inches  from  its 
optical  center.  On  the  other  hand  the  lens  cut  from  the 
outer  circle  would  be  a  7I/>-inch  lens,  because  it  would  focus 
parallel  rays  to  form  an  image  at  a  point  7^2  inches  away; 
that  is  to  say,  it  would  do  so  theoretically.  As  a  matter  of 
fact,  however,  this  is  not  precisely  true,  due  to  the  fact  that 
an  uncorrected  lens  brings  some  rays  to  a  focus  nearer  its 
surface  than  others. 

Spherical  aberration  in  the  condenser  is  governed  by  the 
fact  that  when  parallel  rays  strike  a  plano-convex  lens  on  the 
curved  side  the  spherical  aberration  is  reduced  to  a  minimum, 
but  if  the  rays  be  diverging,  then  the  spherical  aberration 
is  less  if  they  strike  the  piano  side.  This,  of  course,  means 
that  to  secure  the  least  spherical  aberration  the  flat  side  of 
the  rear  lens  must  be  next  the  arc  where  the  rays  are  diverg- 
ing, and  the  convex  side  of  the  front  lens  must  be  toward 
the  arc,  since  it  receives  approximately  parallel  rays  from  the 
rear  lens.  I  mention  this  because  some  operators,  though 
few,  have  a  notion  that  they  gain  advantage  by  placing  the 
curved  side  of  the  front  lens  next  the  machine  aperture.  This 
is  an  error.  In  fact,  the  actuality  is  the  reverse,  although  but 
for  the  element  of  spherical  aberration  there  would  be  little  if 
any  difference  which  way  the  lens  was  placed. 

In  order  to  actually  focus  the  rays  of  light  perfectly  the  lens 
must  be  "corrected"  by  the  addition  of  one  or  more  lenses  having 
negative  curvature. 

As  a  matter  of  fact,  the  surface  of  a  lens  is  really  nothing 
more  or  less  than  millions  of  pin-points,  each  in  effect  a  prism  of 
minute  dimensions.  It  is  a  well  known  fact  that  what  we 
term  "white  light"  is  really  composed  of  a  number  of  colors. 
When  white  light,  or  what  we  call  white  light,  is  passed  through 
a  prism  of  glass,  it  is  more  or  less  separated  into  its  primary 


98  MOTION    PICTURE   HANDBOOK 

colors,  or,  in  other  words,  the  colors  of  which  it  is  composed. 
The  ordinary  plano-convex  is  an  uncorrected  lens,  and  always 
carries  the  fault  of  chromatic  aberration,  which  is  the  property 
of  separating  light  more  or  less  completely  into  its  component 
parts  or  colors.  This  explains  why  you  see  a  fringe  of  color 
at  the  edge  of  the  spot  on  the  cooling  plate  of  the  machine. 

Now,  taking  the  condensing  lens  for  example,  it  being  an 
uncorrected  lens,  remembering  that,  as  I  have  said,  its  surface 
is  composed  of  numberless  minute  prisms,  you  will  readily  see 
that  the  further  away  from  the  center  of  the  lens  you  go  the 
more  acute  will  become  the  angle  of  these  prisms  with  relation 
to  the  light  source,  or  the  light  rays  emanating  from  the  source 
central  with  the  optical  axis  of  the  lens,  and  therefore  the  more 
nearly  true  prism  is  approached.  It  then  follows  that,  since  the 
nearer  we  come  to  the  true  prism  the  greater  will  be  the  light 
separating  power,  we  shall  have  a  greater  amount  of  chromatic 
aberration  at  the  outer  edge  of  the  lens  than  at  its  center.  Near 
the  center  of  the  lens  the  prisms  will  be  very  flat.  Therefore 
their  light-separating  powers  will  be  but  slight;  in  fact,  prac- 
tically nothing  at  all.  At  the  outer  edge  these  powers  will  be 
considerable,  and  here  is  where  one  of  the  evil  effects  of  spherical 
aberration  as  applied  to  projection  makes  itself  apparent. 

As  already  set  forth,  light  rays  near  the  outer  edge  of  a  lens 
will  focus  somewhat  nearer  the  surface  of  the  lens  than  will  rays 
from  near  its  center.  This  means  that  the  excessive  chromatic 
aberration  at  the  outer  edge  of  the  lens  is  mingled  with  the 
purer  light  coming  through  the  center  of  the  lens,  and  the 
quality  of  the  whole  is  thus  injured.  This  is  one  of  the  reasons 
for  my  belief  that  there  is  advantage  in  the  properly  matched 
meniscus-bi-convex  condenser  combination.  The  addition  of 
the  negative  curvature  in  the  meniscus  and  the  extra  curvature 
in  the  bi-convex  makes,  in  effect,  a  three  and  I  believe  a  four 
lens  combination,  which  has  or  ought  to  have  to  a  considerable 
extent  the  effect  of  correcting  spherical  aberration.  I  do  not 
state  this  as  a  positive  fact.  It  has  not  yet  been  proven  to  my 
entire  satisfaction,  but  I  nevertheless  believe  it  to  be  correct. 
There  is,  however,  another  decided  advantage  in  the  use  of  the 
meniscus  lens  next  the  arc,  viz. :  with  a  lens  of  given  focal 
length  the  arc  will  be  nearer  the  meniscus  than  it  would  be 
to  a  piano,  hence  a  much  greater  amount  of  light  will  be 
transmitted  to  the  screen. 

It  is  also  possible  that  a  condensing  lens  with  a  poor,  im- 
perfect surface  would  have  a  considerable  effect  in  injuring 
the  definition  of  the  picture.  This  seems  to  be  made  apparent 
in  Fig.  51,  which  is  a  photograph  of  the  light  ray  from  a  con- 


FOR   MANAGERS   AND   OPERATORS  99 

denser   covered  with   a   metal  plate   in   which    about    a   dozen 
quarter-inch  holes  have  been  drilled  at  various  points. 

This  photograph  proves  conclusively  that  a  light  ray  passing 
through  any  given  point  of  the  condenser  is  carried  forward  to 
the  screen,  where  it  occupies  a  corresponding  and  magnified 
area.  This  being  true,  I  cannot  see  but  that  any  imperfection 
in  the  condensing  lens  which  would  in  the  least  tend  to  alter 
the  direction  of  a  ray  from  the  path  it  would  have  taken  were . 
the  lens  a  perfect  lens  must  of  necessity  injure  the  result  on 
the  screen,  though  Mr.  Griffiths  does  not  agree  with  this  con- 
clusion. However,  I  do  not  care  to  go  deeply  into  this  matter 
at  this  time,  not  being  entirely  sure  of  my  ground. 

The  operator  will  have  noted  the  fact  that  when  the  machine 
head  is  removed,  and  the  white  light  projected  to  the  screen 
without  any  objective  lens,  it  is  impossible  to  bring  the  light 
ray,  as  a  whole,  to  a  sharp  point.  Most  operators  have  hereto- 
fore believed  that  the  rays  from  the  condenser  were  supposed 
to  meet  at  a  point  and  cross  midway  between  the  front  and 
back  factors  of  the  objective  lens.  This  is  not  true.  See  Page  118. 
The  condenser  does  not  bring  the  light  ray  as  a  whole  to  a 
point.  It  forms  an  image  of  the  crater,  and  upon  the  size  of  the 
image  thus  formed  will  depend  the  diameter  of  the  condenser 
light  ray  at  its  narrowest  point.  It  is  a  mistaken  idea  to  suppose 
that  when  we  speak  of  a  lens  "focusing  the  rays"  we  mean  that 
it  brings  the  ray,  as  a  whole,  to  a  sharp  point.  It  does  not.  What 
is  really  meant  is  illustrated  in  Fig.  32.  All  light  rays  emanating 
from  any  pinpoint  of  objective  X  and  reaching  the  surface  of 
the  lens  are  refocused  at  a  similar  point  in  image  Y.  This 
image  may  be  smaller  than  the  original  object.  Study  Fig. 
32,  and  I  think  you  will  get  the  idea. 

The  Objective.— The  objective  lens  of  the  moving  picture 
projection  machine  consists  of  four  lenses,  two  in  the  rear  fac- 
tor and  two  in  the  front  factor.  The  two  at  the  front  are 
usually  cemented  together  with  Canadian  balsam,  so  that,  at  a 
superficial  glance,  they  appear  to  be  one  thick  lens.  As  a 
matter  of  fact  it  is  one  thick  lens,  with  a  thin  one  cemented 
to  the  front  so  that  the  surfaces  of  the  two  lenses  are  brought 
into  contact.  It  sometimes  happens  that  the  heat  will  melt  the 
balsam  and  cause  it  to  run  down  between  the  lenses.  When 
this  happens  it  is  best  not  to  try  to  fix  it  yourself,  but  send  the 
lens  back  to  the  manufacturer  to  be  recemented.  However,  you 
can  separate  the  lenses  (though  I  do  not  advise  you  to  try  it)  by 
proceeding  as  follows :  Set  a  shallow  dish,  filled  with  water,  on 


100 


MOTION    PICTURE    HANDBOOK 


the  stove,  place  the  lens  on  a  large  kitchen  spoon  or  tablespoon 
and  set  the  spoon  in  the  water,  so  that  the  lens  will  be  covered. 
Allow  the  water  to  come  to  a  boil  and  remove  the  lens  quickly, 
shoving  with  your  thumbs  on  one  lens  and  pulling  with  your 
fingers  on  the  other.  It  is  a  pretty  hot  job,  and  you  will  have 
to  use  considerable  force,  but  if  you  bring  the  water  to  a  boil 
it  softens  the  balsam  and  you  can  get  the  lenses  apart.  The 
balsam  can  then  be  washed  off  with  turpentine. 

Distortion. — Operators  should  carefully  test  their  objective 
lenses  for  distortion.  This  may  best  be  done  by  taking  a  per- 
fectly flat  piece  of  mica,  commonly  known  as  isinglass,  three 
or  four  inches  long,  and  cutting  it  to  the  width  of  a  film.  Hav- 
ing done  this,  lay  it  off  checkerboard  fashion,  as  per  Fig.  36, 
and  put  it  in  the  machine,  being  careful  to  get  it  perfectly  flat 


Figure  36. 


B 


over  the  aperture,  and  project  its  image  to  the  screen.  At  A, 
Fig.  36,  we  see  no  distortion.  At  B  there  is  what  is  known 
as  barrel  distortion,  which  amounts  to  a  curvature  of  the  lines. 
The  lens  which  projects  B  is  not  a  good  lens,  whereas  the  lens 
which  projects  A  is  practically  perfect.  The  scratch  marks  on 
the  mica  may  be  made  with  the  point  of  a  knife  blade,  or  any 
other  sharp  instrument.  The  lines  on  the  mica  must  be  perfectly 
straight,  and  if  their  image  on  the  screen  is  not  perfectly 
straight  (test  by  streching  a  line)  the  lens  is  imperfect. 

A  lens  must  focus  all  light  rays  passing  through  a  pinpoint 
in  the  photograph  to  a  corresponding  though  magnified  point 
on  the  screen.  The  distance  at  which  this  focusing  will  be 
accomplished  depends,  within  limits,  upon  the  distance  of  the 
film  from  the  lens — the  back  focus  at  which  the  lens  is  working. 


FOR    MANAGERS    AND   OPERATORS  101 

This  is  diagrammatically  illustrated  in  Fig.  37,  in  which  arrow 
A  is  being  projected  and  focused  at  point  1.  That  is  to  say : 
With  the  arrow  at  the  distance  from  the  lens,  as  shown,  the 
rays  will  meet  and  cross  at  point  1,  where  they  begin  to  diverge. 
If  the  screen  be  placed  at  point  2,  arrow  A  remaining  its 
original  distance  from  the  lens,  instead  of  an  image  on  the 
screen,  each  portion  of  arrow  A  will  be  represented  by  a 
blurred  ring.  If  the  distance  of  arrow  A  from  lens  B  is  altered, 

then  the  distance  at 
which  the  rays  meet 
and  cross  (image) 
will  be  altered,  and 
the  screen  will  have 
to  be  moved  toward 
or  from  the  lens 
a  corresponding  dis- 
tance. This  explains 
Figure  37.  why  it  is  necessary 

to  move  the  lens  in 

and  out  in  order  to  focus  the  picture  on  the  screen.  Where 
the  back  focus  is  short,  as  in  a  moving  picture  lens,  a  slight 
alteration  of  the  distance  between  the  lens  and  the  film  makes 
a  decided  difference  in  the  distance  at  which  the  rays  of  light 
will  focus. 

Doctoring  Lenses. — The  question  is  often  asked:  "Can  the 
E.  F.  of  a  lens  be  altered  by  shortening  or  lengthening  the 
barrel,  so  as  to  alter  the  distance  between  its  two  factors?" 
Yes,  but  it  is  not  advisable  to  try  anything  of  that  sort.  The 
chances  are  that  you  will  ruin  your  lens.  This  scheme  has 
been  known  to  work  fairly  well  in  some  instances,  but  more 
often  than  not  it  is  more  or  less  of  a  complete  failure. 

Bringing  the  two"  combinations  closer  together  or  separating 
them  farther  apart  would  have  the  effect  of  altering  the  size 
of  the  picture  on  the  screen  at  a  given  distance,  but  it  is  a  very 
poor  way  of  doing  it. 

The  author  has  frequently  been  asked  whether  or  not  the 
same  lenses  may  be  used  to  project  a  picture  at  different  dis- 
tances. Yes.  But  it  must  be  understood  that  if  the  distance  be 
made  less,  then  the  picture  will  be  smaller,  and  if  the  distance  be 
made  greater  the  picture  will  be  larger.  Also  moving  the 
screen  will  alter  the  back  focus  at  which  the  lens  will  work. 
The  shorter  the  distance  between  the  lens  and  screen  the  farther 
the  lens  must  be  from  the  film,  and  vice  versa. 


102  MOTION    PICTURE   HANDBOOK 

Spread  of  Ray. — It  is  easy  to  figure  how  much  change  in 
size  of  picture  will  be  accomplished  by  moving  the  screen  any 
given  distance.  Suppose  you  have  a  lens  which  projects  a  10-foot 
picture  at  60  feet.  It  is  readily  seen  that  if  the  width  of  the 
picture  be  divided  by  the  number  of  feet  it  is  projected  the 
result  will  be  the  fraction  of  a  foot  its  width  increases  with 
each  foot  of  distance,  hence  in  this  case  we  have  10  -f-  60  =  one- 
sixth  of  a  foot,  or  2  inches,  which  is  the  amount  the  light  ray 
spreads  for  each  foot  of  distance  between  the  lens  and  screen. 
In  proof  of  this,  multiply  2  X  60  and  we  have  120  inches,  or  10 
feet.  Now,  if  you  move  your  screen  back  five  feet  farther 
you  will  have  2  X  5  =  10  inches  additional  width  of  picture,  or 
if  we  brought  the  screen  6  feet  nearer  the  lens,  then  we  would 
have  2  X  6  =  12  inches  less  width  of  picture. 

Improving  Definition. — The  work  of  a  projection  lens  which 
does  not  give  sharp  definition  may  sometimes  be  improved  by 
cutting  a  circle  of  stiff  dark  paper,  just  large  enough  to  fit 
tightly  into  the  front  end  of  the  lens  barrel  and  up  against  the 
front  lens.  In  the  center  of  this  ring  cut  a  circular  opening, 
the  correct  size  of  which  must  be  determined  by  experiment  in 
each  individual  case.  Usually  it  is  not  advisable  to  stop  down 
more  than  one-fourth  the  diameter  of  the  opening.  This  is 
often  of  benefit  in  sharpening  the  focus  where  the  machine  sets 
above  or  to  one  side  of  the  screen,  because  reducing  the  lens 
diameter  has  the  effect  of  increasing  its  depth  of  focus. 

Dirty  Lenses. — It  is  of  the  utmost  importance  that  the 
operator  keep  his  lenses  scrupulously  clean.  "Optical  Projec- 
tion," by  Simon  Henry  and  Henry  Phelps  Gage,  gives  the  losses 
by  reflection  from  the  polished  surface  of  each  surface  to  each 
lens  as  from  4  to  5  per  cent.,  or  a  total  of  8  to  10  per  cent,  for 
each  lens  or  plate  of  glass,  and  further  remarks  that  if  the 
surface  of  the  glass  be  not  perfectly  clean  or  perfectly  polished 
the  light  loss  may  amount  to  much  more — say  15  per  cent,  at 
each  surface. 

It  really  seems  to  me  that  this  cannot  be  true.  There  being 
eight  surfaces  in  an  objective  lens,  or  since  two  of  them  are 
in  direct  contact,  let  us  say  six,  even  taking  the  lowest  figure, 
viz.,  4  per  cent,  for  each  surface,  we  would  have  a  total  of 
24  per  cent,  loss  by  reflection  alone.  However,  without  dis- 
cussing the  probable  correctness  of  the  percentages,  it  is  an 
undoubted  fact  that  there  is  considerable  loss  through  reflec- 
tion, and  this  loss  will  be  very  largely  increased  if  the  lens  be 
dirty.  Therefore,  it  is  very  much  up  to  the  operator  to  keep 
his  lenses  not  only  clean  but  polished  as  highly  as  possible, 


FOR   MANAGERS   AND   OPERATORS  I03 

Measuring  Lenses  is  a  very  simple  operation.     In  order 

properly  to  match  up  a  projector  lens  system  it  is  necessary 
that  the  operator  be  able  to  measure  and  determine  the  exact 
focal  length  of  his  condenser  lenses,  and  it  is  often  very  desirable 
that  he  be  able  to  measure  the  exact  equivalent  focus  of  an 
objective  in  order  that  he  may  determine  what  size  picture  it 
will  project  at  a  given  distance. 

Plano-convex  lenses  may  be  measured  as  follows:  Pin  a 
sheet  of  white  paper  to  the  wall  of  a  room,  opposite  a  window, 
hold  the  lens  up  with  its  flat  side  toward  the  wall  and,  through 
the  open  window,  carefully  focus  some  building,  trees,  or  other 
object  located  at  a  considerable  distance  outside  the  window, 
on  the  paper  screen.  It  is  essential  to  accuracy  that  the  object 
being  focused  be  a  goodly  distance  away — the  farther  the  better 
— because  in  these  measurements  the  light  rays  are  presumed 
to  enter  the  lens  in  parallel  lines,  and  unless  they  do  enter  in 
approximately  parallel  lines  there  will  be  error  in  the  result. 
Be  sure  to  get  the  lens  in  exact  position  where  the  focus  of  the 
image  on  the  paper  screen  is  most  sharp,  and  then  measure  from 
the  flat  side  of  the  lens  to  the  wall,  making  a  note  of  the  pre- 
cise distance.  Next  turn  the  lens  around  and  with  the  convex 
side  toward  the  wall,  again  carefully  focus  the  same  object 
on  the  paper  screen  and  measure  from  the  wall  to  the  flat  side 
of  the  lens.  It  will  be  found  that  the  two  measurements  will 
differ  considerably,  and  their  sum  divided  by  2  will  be  the  focal 
length  of  the  lens.  For  instance:  Suppose  one  measurement  to 
be  6  inches  and  the  other  7  inches :  6  +  7  =  13  which  divided 
by  2  =  6H>  therefore  it  is  a  6l/2  inch  lens. 

It  is  not  practical  to  measure  condensing  lenses  with  any 
great  degree  of  accuracy.  There  is  so  much  spherical  aberra- 
tion in  these  uncorrected,  comparatively  cheap  lenses,  that  the 
picture  cannot  be  focused  with  absolute  sharpness.  The  focal 
length  of  the  lens  may,  however,  be  arrived  at  by  the  fore- 
going process  closely  enough  to  serve  all  practical  purposes. 

The  measuring  of  a  motion  picture  objective  or  stereopticon 
lens  is  a  very  simple  operation.  The  focus  of  a  projection 
lens  may  be  designated  in  two  ways — viz.,  back  focus  (common- 
ly expressed  as  b.  f.)  which  is  the  measurement  often  used  by 
the  film  exchange,  and  equivalent  focus  (commonly  expressed 
as  e.  f.),  which  is  the  measurement  used  by  the  lens  manufac- 
turer. Therefore  in  ordering  lenses  of  a  given  focal  length 
one  should  be  careful  to  state  whether  the  measurement  given 
represents  b.  f.  or  e.  f.  The  e.  f.  is  the  measurement  which  must 
be  used  in  ordering  lenses  to  project  a  picture  of  given  distance. 


104  MOTION    PICTURE    HANDB6OK 

To  measure  a  moving  picture  objective  or  stereopticon  lens 
pin  a  sheet  of  white  paper  to  a  wall  opposite  a  window.  Hold 
the  lens  square  with  the  paper  screen  and,  through  the  open 
window,  focus  some  building,  tree,  or  other  distant  object  on 
the  paper  screen;  be  very  careful  to  get  the  image  as  sharp  as 
you  possibly  can.  Now  measure  from  the  wall  to  the  surface 
of  the  lens  nearest  the  screen,  and  that  measurement  will  be 
the  back  focus,  or  b.  f.  of  the  lens.  If,  instead  of  measuring 
from  the  surface  of  the  lens  to  the  screen,  you  measure  from  a 
point  half  way  between  the  front  and  back  combinations  of  the 
lens  (half  way  between  the  lenses  at  either  end  of  the  tube)  to 
the  paper  screen,  that  measurement  will  be  the  equivalent  focus, 


i 
I  i 


i 


i  r  M  1 1 1 1 1  <  i '  i '  i  >  i '  i '  i  >  i '  i  M  1 1 


Figure  38. 

or  e.  f.  of  the  lens.  In  other  words. the  e.  f.  is  equal  to  the  b.  f. 
plus  half  the  distance  between  the  two  combinations  of  the  lens. 
All  this  we  see  diagrammatically  represented  in  Fig.  38. 

Again  let  me  caution  you  always  to  focus  some  DISTANT  object; 
an  object  which  is  100  feet  away  will  do,  and  even  an  object  25 
feet  away  will  not  be  close  enough  to  affect  the  result  very 
much.  It  is  even  possible  to  get  an  approximate  measurement  by 
focusing  an  incandescent  light,  provided  it  be  at  least  10  or  15 
feet  away,  but  such  a  measurement  cannot  be  depended  upon 
when  accuracy  is  essential.  Also  see  Page  108. 

The  use  of  these  measurements,  as  applied  to  the  objective, 
becomes  apparent  when  we  learn  that  the  size  of  the  picture 
which  will  be  projected  by  any  lens  at  a  given  distance  from 
the  screen  will  be  entirely  dependent  upon  the  focal  length  of 
the  lens.  The  shorter  its  focal  length  the  larger  will  be  the 


FOR   MANAGERS    AND    OPERATORS  105 

picture  at  a  given  distance,  and  the  longer  its  focal  length  the 
smaller  will  be  the  picture  at  a  given  distance.  A  lens  having 
a  4-inch  e.  f.  will  project  a  much  larger  picture  at  50  feet  than 
will  a  lens  having  a  6-inch  e.  f. 

Nearly  all  machine  and  lens  manufacturers  put  out  tables  de- 
signed to  tell  one  the  exact  size  (width)  picture  a  lens  of  given 
focal  length  will  project  at  a  given  distance.  These  tables  are 
useful  as  applied  to  stereopticon  lenses,  but  have  slight  value 
as  applied  to  the  moving  picture  objective — this  by  reason  of 
the  fact  that  the  size  of  picture  is  based  upon  a  given  width  of 
aperture,  which,  in  the  case  of  the  stereo,  is  supposed  to  be  3 
inches,  but  which  may  vary  widely  with  each  set  of  slides 
(the  aperture  in  the  case  of  the  stereopticon  is  the  width  of 
the  standard  slide  mat)  ;  hence,  by  reason  of  the  variation  in 
the  size  of  slide  mats  it  is  impossible  to  figure  the  size  of  a 
stereopticon  picture  with  any  degree  of  accuracy,  and  the  table 
will  therefore  answer  about  as  well  as  measurements. 

As  applied  to  the  motion  picture  objective,  however,  these 
tables  are  not  at  all  satisfactory.  As  a  rule  operators  and  man- 
agers want  their  picture  not  approximately,  but  exactly  a  given 
width.  Now  there  are  at  the  present  time  two  different  stand- 
ards of  motion  picture  machine  aperture  widths,  viz.,  15/16  and 
29/32;  also  the  aperture  of  the  older  machines  of  different 
makes,  while  they  were  presumed  to  be  all  15/16  of  an  inch, 
really  varied  considerably,  and  a  slight  variation  would  make 
.considerable  difference  in  the  size  of  the  picture  on  the  screen, 
as  for  instance,  if  you  used  15/16  of  an  inch  as  a  basis  for 
figuring,  and  the  aperture  really  was  a  little  more  or  a  little  less 
than  that  width,  then  the  result  would  be  a  picture  wider  or 
narrower  than  your  figures  called  for.  This  being  the  con- 
dition, you  can  readily  see  that  tables  cannot  be  depended  upon 
for  any  very  great  degree  of  accuracy  in  results..  I  will,  how- 
ever, for  reasons  already  set  forth,  append  one  of  the  tables 
for  stereopticon  lenses. 

To  figure  the  necessary  equivalent  focus  of  a  lens  to  project 
a  picture  of  given  width  at  a  given  distance  proceed  as  follows : 
Have  a  machinist  measure  the  aperture  of  your  machine  ac- 
curately with  an  inside  caliper  and  a  micrometer.  Measure  the 
exact  distance  from  the  lens  to  the  screen.  Multiply  the  dis- 
tance from  the  lens  to  the  screen,  in  feet,  by  the  width  of  the 
aperture,  in  fractions  of  an  inch,  and  divide  the  result  by  the 
width  of  the  picture  you  desire,  in  feet.  The  result  will  be  the 
c.  f.  of  the  lens  required  to  project  a  picture  that  width,  and  will 
be  as  close  to  it  as  you  can  get  at  it  by  figuring.  For  instance : 
Suppose  you  want  a  15-foot  picture  at  60  feet,  The  machine 


106  MOTION    PICTURE   HANDBOOK 

aperture  is  found  to  be  29/32  of  an  inch  (the  new  standard) 
wide.  First  multiply  the  distance  from  the  screen  in  feet  by 
the  width  of  the  aperture  in  fractions  of  an  inch.  To  multiply 
60  by  29/32  we  first  divide  by  32  and  multiply  the  result  by  29 ; 
60-7-32—1.875;  1.875X29=54.375.  Next  we  divide  this 
measurement  by  the  desired  width  of  picture  in  feet:  54.375 -^  15 
=  3.625,  or  a  3^?-inch  e.  f.  lens.  We  most  likely  would  be  un- 
able to  get  that  exact  focal  length  and  would  have  to  take,  in- 
stead, a  524-inch  e.  f.  lens. 

It  must  be  understood,  however,  that  the  great  bulk  of  pro- 
jection lenses  now  in  use  are  cheap  lenses,  and  cheap  lenses, 
like  all  other  cheap  things,  are  inaccurate,  therefore  you  can- 
not expect  to  arrive  with  certainty  at  precisely  the  result  you 
desire  in  any  other  way  than  by  actually  testing  the  lenses. 

The  stereopticon  lens  is  figured  exactly  the  same  way,  except 
that  instead  of  measuring  the  aperture  width,  we  take  3  inches 
as  the  average  width  of  the  slide  mat— the  slide  mat,  in  this 
case,  being  the  aperture. 

It  is  also  entirely  practical  to  make  other  measurements  of 
practical  value  as  follows:  Suppose  you  have  an  objective  and 
wish  to  know  what  size  picture  it  will  project  at  a  given  dis- 
tance. First  measure  its  e.  f.  as  already  directed  and  then: 

Size  of  Image. — This  can  be  determined  by  multiplying  the 
difference  between  the  distance  from  lens  to  screen  and  the 
focal  length  of  the  objective,  by  the  width  of  the  aperture  and 
dividing  the  pro-rlurt  by  the  focal  length  of  the  lens.  For  ex- 
ample: Let  L  be  the  projection  distance,  40  feet  (480  inches); 
S,  the  slide  mat,  3  inches;  F  the  e.  f.  of  the  lens,  12  inches; 
we  then  have  the  formula  (in  which  d  is  the  size  of  image) ; 

S  (L-F) 


F 

Substituting  for  the  letters  their  known  values,  we  have: 
3  (480—12) 


=117  in.,  or  9^  feet, 


12 

as  the  size  picture  a  12-inch  e.  f.  stereo  lens  will  project  at  40 
feet,  provided  the  slide  mat  be  just  3  inches  wide.  If.  how- 
ever, the  mat  be  more  or  less  than  3  inches,  then  the  picture 
will  be  wider  or  less  wide. 

Distance  from  Slide  to   Screen.  —  With   the   other   factors 
given  we  get  this  by  multiplying  the  sum  of  the  width  of  the 


FOR   MANAGERS   AND   OPERATORS 


107 


Showing  Size  of  Screen  Image  When  Lantern  Slides 
Are  Projected 

Size  of  Mat  Opening,  2^x3  Inches 
Table  7,  Figure  39 


Equlv.  focus 
Inches 

15 
ft. 

20 

ft. 

25 
ft. 

30 

ft. 

35 
ft. 

40 
ft. 

45 
ft. 

bO 

ft. 

BO 
ft. 

70 

ft. 

80 
ft. 

30 
ft. 

100 

ft. 

5 

8.0 

10.8 

13.5 

18.3 

19.0 

8.8 

11.8 

14.8 

17.8 

20.8 

5/4 

7.3 

9.8 

12.3 

14.8 

17.3 

19.8 

7.9 

10.7 

13,4 

18.1 

18.8 

21.6 

1 

6.6 

8.9 

11.2 

13.5 

15.8 

18.1 

20.4 

7.3 

9.8 

12.3 

14.8 

17.3 

19.8 

22.3 

IK 

6.1 

8.2 

10.4 

12.5 

14.6 

18.7 

18.8 

6.7 

9.0 

1.1.3 

13.6 

15.9 

18.2 

20.5 

1 

5.7 

7.6 

9.6 

11.6 

13.5 

15.5 

17.5 

19.4 

6.2 

8.3 

10.5 

12.6 

14.8 

16.9 

19.0 

21.2 

1% 

5,3 

7.1 

8.9 

10.8 

12.6 

14.4 

16.3 

18.1 

5.6 

7.8 

9.8 

11.8 

13.8 

15.8 

17.8 

19.8 

6 

6.8 

8.4 

10.1 

11.8 

13.5 

15.2 

17.0 

204 

7.3 

9.1 

11.0 

12.9 

14.8 

16.6 

18.5 

223 

8% 

6.2 

7.9 

9.5 

11.1 

12.7 

14.3 

16.0 

19.2 

6.8 

8.8 

10.3 

12.1 

13.9 

15,6 

17.4 

20.9 

1 

5.9 

7.4 

8.9 

10.5 

12.0 

13.5 

15.1 

18.1 

21.1 

6.4 

8.1 

9.8 

11.4 

13.1 

14.8 

16.4 

19.8 

23.1 

BK 

5.6 

7.0 

8.5 

9.9 

11.4 

12.8 

14.2 

17.1 

26.0 

6.1 

7.8 

9.2 

10.8 

12.4 

14.0 

15.5 

18.7 

21.9 

10 

5.3 

6.6 

8.0 

9.4 

10.8 

12.2 

13.5 

16.3 

19.0 

21.8 

5.8 

7.3 

8.8 

10.3 

11.8 

13.3 

148 

17.8 

20.8 

23.8 

12 

5.5 

6.6 

7,8 

8.9 

10.1 

11.2 

13.5 

15.8 

18.1 

20.4 

8.0 

7.3 

8.5 

9.8 

11.0 

12.3 

14.8 

17.3 

19.8 

22.3 

14 

5.6 

6.6 

7.8 

8.8 

9.6 

11.6 

13.5 

15.5 

17.5 

19.4 

6.2 

7.3 

8.3 

9.4 

10.5 

12.6 

14.8 

16.9 

19.0 

21.2 

16 

5.8 

6.6 

7.5 

8.4 

10.1 

11.8 

13.5 

152 

17.0 

6.3 

7.3 

8.2 

9.1 

11.0 

12.9 

14.8 

16.6 

18.5 

18 

5.1 

5.9 

6.6 

7.4 

8.9 

10.5 

12.0 

13.5 

15.1 

5.6 

8.4 

7.3 

8.1 

9.8 

11.4 

13.1 

14.8 

if.  4 

20 

5.3 

6.0 

8.6 

8.0 

9.4 

10.8 

12.2 

13.5 

5.8 

8.5 

7.3 

8.8 

10.3 

11.8 

13.3 

14.8 

22 

5.4 

6.0 

7.3 

8.5 

9.8 

11.0 

12.3 

5.9 

6.6 

7.9 

9.3 

10.7 

12.0 

13.4 

24 

5.5 

6.8 

7.8 

8.9 

10.1 

11.2 

6.0 

7.3 

8.6 

9.8 

11.0 

12.3 

EXAMPLE:  With  a  lens  of  10-inch  focus  at  a  distance  of 
20  ft.  the  screen  image  will  be  5.3  x  5.8;  at  25  ft.,  6.6  x  7.3; 
at  30  ft.,  8.0  x  8.8;  at  50  ft.,  13.5  x  14.8  etc. 


108  MOTION    PICTURE   HANDBOOK 

image  and  width  of  the  slide  mat,  by  the  focal  length  of  the 
lens  ;  dividing  this  product  by  the  width  of  the  slide  mat,  thus  : 

F(d  +  S) 

T      _   ________ 


12(117  +  3) 

Substituting  values,  L  =  —  —  —  480  inches  =  40  feet. 

3 

Measuring  E.  F.  Accurately.  —  Should  the  operator  desire 
to  measure  the  e.  f.  of  his  objective  with  absolute  accuracy 
he  may  proceed  as  follows:  Remove  the  mechanism  and  in 
the  position  the  aperture  of  the  machine  occupied  place  a 
sheet  of  tin  having  an  aperture  about  three-quarters  of  an 
inch  square.  Now  hold  the  lens  out  at  a  distances  about 
twice  the  length  of  its  supposed  e.  f.,  in  front  of  the  aperture, 
with  the  light  turned  on,  and  an  equal  distance  in  front  of 
the  lens  (still  further  out)  hold  a  small  screen,  preferably 
dull  black  in  color,  and  move  the  lens  and  the  screen  until 
the  image  of  the  aperture  on  the  screen  is  exactly  the  same 
width  as  the  actual  aperture.  Now  measure  the  distance  from 
the  aperture  to  the  screen  and  divide  it  by  4;  the  result  will 
be  the  exact  e.  f.  of  the  lens. 

Cleaning  Lenses.  —  It  is  of  the  utmost  importance  that 
lenses  be  kept  scrupulously  clean.  Oil  and  fingermarks  are 
particularly  objectionable.  I  have  been  called  to  theaters 
to  locate  the  cause  of  lack  of  sharp  focus  in  the  picture,  only 
to  find  that  the  operator  had  had  his  objective  apart  to  clean, 
and  in  putting  it  together  had  inadvertently  lightly  touched 
one  of  the  interior  surfaces  of  the  lens  with  his  finger.  The 
mark  was  so  slight  that  it  could  not  be  detected  by  looking 
through  the  lens,  but  was  quite  visible  when  the  lens  was 
taken  apart  and  looked  at  from  an  angle.  Slight  as  this  mark 
was  it  seriously  injured  the  definition  of  the  picture. 

Oil  on  the  surface  of  a  lens  will  also  operate  to  injure  the 
focus  of  the  picture.  I  do  not  think  any  argument  is  neces- 
sary on  this  particular  point. 

It  is  absolutely  essential  to  sharp  definition  of  the  picture  on 
the  screen  that  all  lenses  be  kept  scrupulously  clean. 

The  careful  painstaking  operator,  whose  machines  run  several 
hours  each  day,  will  clean  his  condensing  lenses  every  day,  par- 
ticularly the  one  next  the  arc.  The  objective  lens  need  not 
be  cleaned  more  than  perhaps  once  a  week,  unless  oil  spatters 
on  its  rear  surface,  in  which  case  it  should  be  cleaned  just 
as  soon  thereafter  as  possible,  and  if  there  is  tendency  of  oil 


FOR   MANAGERS    AND    OPERATORS  109 

to  spatter  on  the  lens  its  rear  end  should  be  protected  by 
some  kind  of  a  metal  guard.  I  cannot  tell  you  just  now  how 
to  do  this,  because  the  method  would  vary  with  different 
mechanisms,  but  certainly  the  competent  operator  can  devise 
ways  and  means  to  keep  the  oil  off  the  rear  end  of  his  lens. 
In  some  cases  a  collar  of  tin  made  tight  enough  to  clamp  the 
rear  end  of  the  lens  barrel,  extending  back  nearly  to  the 
aperture,  will  answer  the  purpose. 

Unless  there  is  oil  on  the  lens  I  know  of  no  better  way  of 
cleaning  them  than  by  breathing  on  the  cold  glass  and  polish- 
ing with  a  perfectly  cle  n  chamois,  or  an  old,  clean,  soft 
handkerchief.  Always  provided  there  be  no  oil  present,  this 
twill  clean  the  surface  of  the  lens  perfectly,  and  will  answer 
every  purpose.  If  there  be  oil  on  the  lens,  then  I  recom- 
mend the  use  of  a  solution  of  one  half  alcohol  and  one  half 
water.  Wash  the  lens  off  with  a  cloth  saturated  with  the 
solution,  and  polish  quickly  with  a  dry,  soft,  clean  hand- 
kerchief, perferably  an  old  one.  Nothing  makes  a  better  lens 
cloth  than  an  old,  worn  out  handkerchief,  after  having  been 
laundered.  Some  operators  prefer  a  solution  of  ammonia  and 
water  or  water  and  alcohol. 

The  operator  should,  perhaps  twice  a  year,  take  his  ob- 
jective lenses  apart  and  clean  their  interior  surfaces,  being 
very,  very  careful  that  in  putting  them  back  he  does  not 
touch  their  surface  with  his  fingers.  This  latter  is  of  the 
utmost  importance,  because  the  very  lightest  touch  will  leave 
a  mark  which,  while  invisible  when  looking  through  the  lens, 
is  likely  to  seriously  injure  its  work.  In  replacing  the  ob- 
jective lens  factors  always  put  them  together  so  that  the 
heavy  bulge  or  convex  of  all  lenses  is  toward  the  screen. 
In  taking  out  the  rear  combination  be  careful  that  you  put 
them  back  in  the  same  position  they  were  in.  In  other 
words,  don't  get  their  position  switched.  The  best  way  to 
go  about  this  is  to  lay  a  sheet  of  paper  on  a  table  and  write 
"rear  lens,"  "inside  lens,"  and  "front  lens,"  at  different  places 
on  its  surface.  Now  as  you  take  the  lenses  out  lay  the  rear 
one  (next  the  aperture)  on  the  space  marked  "rear  lens," 
the  inside  one  on  the  next  space,  and  the  front  on  the  space 
marked  "front  lens."  Then  you  cannot  very  well  make  any 
mistake.  You  will  find  a  spacing  ring  between  the  two  rear 
lenses.  Be  sure  and  get  it  back  in  its  place  when  you  put 
the  lenses  together. 

Fig.  40|  shows  the  position  of  the  lenses  in  an  objective. 
The  two  front  lenses  are  cemented  together  with  Canadian 
balsam.  (See  Page  100.) 


110 


MOTION    PICTURE   HANDBOOK 


Selecting   Condensing  Lenses. — See   Page  127. 

Lens  Diameter. — Lens  diameter  is  a  subject  of  much  im- 
portance. With  a  point  source  of  light  it  would  be  quite 
impossible  to  use  a  very  small  diameter  and  place  the  arc 
right  up  close  to  it.  Modern  practice,  however,  is  to  use  an 
amperage  for  the  projeection  of  moving  pictures  which  pro- 
duces a  crater  varying  from  (D.  C.)  one-quarter  to  one-half 
inch  in  diameter.  This,  of  course,  means  a  light  source  of 
very  high  temperature,  and  more  or  less  naming  of  the  car- 
bons, so  that  the  light  source  cannot  be  brought  very  close 
to  the  lens.  So  far  as  the  condenser  be  concerned,  as  a  rule 
the  diameter  of  the  lens  next 
the  arc  might  be  4  inches  as 
against  a  4%-inch  diameter 
for  the  rear  lens  without  in- 
creasing light  loss;  this  by 
reason  of  the  fact  that  the 
condenser  next  the  arc 
usually,  with  the  arc  in  oper- 
ating position,  produces  a 
diverging  ray  beyond  the 
lens,  and  it  is  only  necessary 
that  the  front  lens  have  suf- 
ficient diameter  so  that  the 

light  from  it  will  just  cover  the  front  lens.  This  is  not  intended 
to  mean  that  the  author  expects  any  change  of  this  kind  will 
be  made.  It  is  simply  an  interesting  point,  though  in  Eng- 
land and  Germany  use  is  made  of  a  lens  next  the  arc  which 
has  a  smaller  diameter  than  the  front  lens.  Four  and  a  half 
inches  seems  to  be  fairly  satisfactory  diameters  for  con- 
densers. Whether  there  would  be,  considering  the  proposi- 
tion as  a  whole,  any  gain  in  using  a  larger  diameter  con- 
denser I  am  not  quite  sure,  but  doubt  it. 

The  diameter  of  the  objective  lens  is  a  matter  of  the  utmost 
importance.  See  Page  121  and  Fig.  49. 

High-Grade  Lenses.— The  author  of  this  work  is  thoroughly 
and  completely  convinced  that  it  is  a  tremendous  mistake 
to  use  cheap  objective  lenses  for  projecting  the  picture.  This 
most  emphatically  is  not  the  result  of  snap-shot  judgment, 
but  a  conviction  which  has  been  growing  for  some  years 
which  was  finally  clinched  by  knowledge  of  the  fact  that  the 
better  English  theaters  are  using  lenses  costing  as  much  as 
£12  (approximately  $60),  supplemented  by  absolute  proof 
that  there  is  a  very  large  possible  gain  in  illumination 
and  sharpness  of  focus  by  using  a  high  class  objective  lens. 


Figure  40. 


FOR   MANAGERS   AND   OPERATORS  111 

The  projection  of  the  picture  is  nothing  more  or  less  than 
a  reversal  of  the  process  of  its  photographing.  Film  manu- 
facturers spare  no  expense  in  procuring  the  best  lens  obtain- 
able for  their  cameras.  These  lenses  are  a  magnificent  ex- 
ample of  the  optician's  art.  They  must  have  great  "depth" 
and  plenty  of  "speed."  They  must  be  corrected  for  about 
every  imaginable  fault,  and  the  result  is  that  they  register 
on  the  film  a  wealth  of  detail,  depth,  and  sharpness  which 
are  largely  lost  by  reason  of  the  fact  that  the  photograph 
must  be  projected  by  about  the  cheapest  lens  it  is  possible 
to  obtain. 

Authorities  in  England,  where]  they  have  already  made 
considerable  progress  in  the  high-grade  projection  lens 
business,  claim  that  in  order  to  get  a  perfectly  flat  field  it  is 
necessary  that  an  anastigmat  lens  be  used.  I  cannot  vouch 
for  the  correctness  of  this,  but  am  told  by  lens  men  here  in 
America  that  it  is  true. 

These  same  authorities  who  have  experimented  with  ihigh- 
class  objectives  for  the  projection  of  pictures  claim  that 
the  high-class  lens  will  pay  its  additional  cost  within  a  com- 
paratively short  time  in  current  saving,  it  being  the  fact  that 
these  lenses  give  a  greater  illumination  per  ampere  of  cur- 
rent than  do  the  ordinary  objectives  now  being  used.  This 
I  personally  have  seen  demonstrated. 

Just  reason  with  yourself  for  a  moment.  If  the  cheap  leni 
is  the  right  thing  with  which  to  project  a  picture,  then  why 
is  it  not  the  proper  thing  to  take  the  picture  with?  Why 
take  a  picture  with  a  costly,  high-class  lens  and  project  it 
with  a  cheap,  comparatively  poor  article.  It  doesn't  sound 
like  common  sense,  does  it,  gentlemen? 

I  notice  that  no  less  a  person  than  Simon  Henry  Gage, 
Cornell  University,  a  man  deeply  versed  in  the  science  of 
optics,  in  his  work  on  "Optic  Projection,"  says  there  is  no 
particular  value  in  having  a  perfectly  sharp  picture  if  it  is 
to  be  viewed  at  a  considerable  distance.  He  even  says  a 
little  coarseness  is  an  advantage.  With  this  I  cannot  at  all 
agree.  I  have  the  utmost  respect  for  the  knowledge  of 
Professor  Gage,  but  in  this  one  particular  thing  I  think 
he  is  decidedly  in  error,  and,  moreover,  assuming  he  is  right, 
it  must  be  remembered  that  a  goodly  portion  of  the  audience 
is  seated  compartively  near  the  screen. 

The  writer  makes  no  claim  to  being  an  expert  in  lenses — 
far  from  it.  He  does,  however,  claim  to  be  the  possessor 
of  a  considerable  fund  of  common  sense,  and  common  sense 
tells  him  that  the  sharper  the  picture  is  the  better  for  all 


112 


MOTION    PICTURE    HANDBOOK 


concerned.  Moreover,  flatness  of  field  is  to  be  highly  de- 
sired, since  curvature  of  field  means  there  will  be  a  tendency 
to  out-of-focus  effect  at  the  edges  when  the  center  is  in 
focus,  and  vice  versa.  This  may  or  may  not  be  sufficient  to 
be  noticeable,  but  is  apt  to  be  very  much  so  with  short  focal 
length  lenses.  It  is  in  the  nature  of  things,  and  cannot  be 
otherwise  unless  the  lens  is  corrected  to  produce  a  flat  field, 
and  as  I  understand  it  that  means  an  anastigmat  lens. 

I  would  strongly  advise  theatre  managers  to  purchase  high- 
class  lenses  for  their  projectors.  I  would  even  advise  them 
to  have  no  hesitation  in  paying  as  much  as  sixty  dollars  for 
a  good  lens.  The  Kleine  Optical  Company,  Chicago,  is 
handling  high-grade  lenses.  The  Dallmyer  lenses  are  handled 
by  Burke  &  Jones,  New  York  City  and  Chicago,  and  the 
other  European  manufacturers  producing  high-class  pro- 
jection lenses  also  have  their  representatives  in  this  country. 

Just  at  present  it  may  be  difficult  to  secure  just  the  right 
kind  of  lens,  but  I  have  had  proof  of  the  fact  that  the  lenses 
handled  by  Mr.  Kleine,  listed  from  thirty  to  sixty  dollars,  are 
a  very  good  article,  and  worth  every  cent  of  their  price. 


LINING  THE   OPTICAL  SYSTEM 

In  order  to  insure  the  best  possible  results  on  the  screen 
it  is  essential  that  the  light  source  (crater),  the  optical  axis 
of  both  condensing  lenses,  and  the  optical  axis  of  both  com- 
binations of  the  objective  be  exactly  in  line  and  square  with 


Figure  41. 


each  other,  and  that  a  line  drawn  through  the  optical  axis  of 
the  lens  system  shall  pass  precisely  through  the  center  of 
the  aperture  of  the  projector. 


FOR   MANAGERS    AND   OPERATORS  113 

In  Fig.  41,  A  is  the  crater,  B  the  lamphouse  condenser 
opening  with  the  condensers  removed,  D  the  aperture  of 
the  projector,  E  the  objective  lens  barrel,  with  the  lenses  re- 
moved, and  F  the  opening  in  the  wall  of  the  operating  room. 
H  is  a  stand  of  white  sewing  thread  or  a  fine  copper  wire, 
G  is  a  light  metal  rod  placed  across  the  opening  in  the  opera- 
ting room  wall,  and  supported  by  string  H  being  drawn  taut 
The  method  of  procedure  is  as  follows:  First  remove  the 
condensing  lenses  and  remove  the  lens  factors  from  the 
objective,  but  leave  the  barrel  screwed  firmly  in  its  place 
in  the  lens  ring.  Next  attach  cord  or  wire  H  to  rod  G,  and 
pass  the  cord  or  wire  through  the  lens  barrel  and  machine 
aperture,  as  shown,  and  bring  it  back  and  tie  it  around  the 
point  of  the  upper  carbon.  After  all  is  ready  pull  the  lamp 
back  by  its  forward  and  backward  adjustment  (before 
beginning  it  should  be  shoved  clear  ahead)  until  string  or 
wire  H  is  pulled  tight — just  tight  enough  so  that  rod  G-  will 
be  held  in  place  and  the  string  or  wire  be  perfectly  straight. 
Now  with  caliper  C  carefully  center  cord  or  .wire  H  in  con- 
denser opening  B,  machine  aperture  A,  and  both  ends  of 
objective  lens  barrel  E,  moving  whatever  may  be  necessary 
to  accomplish  the  purpose.  I  cannot  tell  you  what  you  will 
have  to  do  to  get  the  string  in  the  center  since  this  will  vary 
in  different  cases :  it  will  have  to  be  left  to  your  ingenuity. 

No  attention  should  be  paid  to  hole  F  in  the  wall  as  that 
has  nothing  whatever  to  do  with  the  lining  except  to  sup- 
port rod  G  which  holds  the  string  in  place.  The  fastening 
of  the  cord  to  the  carbon  point  will  be  facilitated  by  using 
a  three  cornered  file  and  filing  a  small  notch  at  N. 


Matching  Up  the  Lens  System 

THE   action  of  light   rays  through    a  projection   system 
has    been    the    subject    of    mudh    controversy,    and    I 
believe    it    might   fairly    be    said    that    until    the    pro- 
jection   Department   of   the   Moving   Picture    World   undertook 
a  series  of  experiments  and  went  into  an  exhaustive  study 
of  the  matter,  no  very  intelligent  explanation  of  the  action 
of  light  rays   through   the   projector  system  had   ever  been 
promulgated — that  is  to  say,  no  explanation  which  "squared 
up"  with  what  apparently  actually  took  place. 

The  main  stumbling  block  in  this  proposition  lay  in  the 
fact  that  the  same  conditions  do  not  obtain  in  the  projection 
of  moving  pictures  that  obtain  in  stereopticon  projection;  a 


114  MOTION   PICTURE   HANDBOOK 

fact  which  opticians  have  failed  to  observe,  attacking  the 
problem  of  projecting  moving  pictures  from  the  same  stand- 
point as  of  projection  lantern  slides.  The  difference  in  the 
two  problems  lies  in  the  following:  In  stereopticon  projec- 
tion the  object  (slide)  is  situated  right  up  against  the  con- 
densing lens,  whereas  in  moving  picture  projection  the  ob- 
ject (film),  is  at,  or  near  the  crater  image — a  foot  or  more 
away  from  the  condenser,  and  at  one  of  the  conjugate  foci 
points  of  the  condenser  system.  This  means  that  the  two 
problems  present  very  different  angles.  In  order  to  obtain 
maximum  illumination  in  stereopticon  projection  the  crater 
image  must  'be  approximately  central  between  the  two  factors 
of  the  stereopticon  objective  lens,  whereas  in  moving  picture 
projection  it  must  be  at  or  near  the  object  (film). 

The   author   does  not  believe   this   matter   to   be,   as   yet, 
entirely    solved,    but    he    does    believe    that    great    progress 


Plate  1,  Figure  42. 

has  been  made,  and  that  the  tables  representing  that  progress 
which  are  hereto  appended  will  be  found  to  be  approx- 
imately correct,  and  that  they  will,  barring  the  limits  imposed 
by  present  day  apparatus,  enable  the  operator  to  match  up 
his  projector  lenses  in  a  way  to  give  very  satisfactory  results. 
In  this  connection  we  are  especially  indebted  to  John 
Griffiths,  Ansonia,  Conn.;  W.  S.  James,  formerly  of  Camden, 
N.  J.;  C.  D.  Armstrong,  Ashland,  Wis.;  and  L.  C.  LaGrow, 
Albany,  N.  Y.  These  men  have  aided  very  greatly  in  the 
solving  of  this  difficult  problem  and  Griffiths  has  contributed 
the  greater  portion  of  the  theory  upon  which  the  tables  are 
based,  as  well  as  worked  out  the  tables  themselves. 


FOR   MANAGERS   AND   OPERATORS 


115 


The  Condenser. — The  spacing  of  the  two  condenser  lenses 
different  distances  apart  has  the  effect  of  altering  the 
equivalent  focus  of  the  combination.  The  further  the  lenses 
are  spaced  apart  the  longer  will  be  the  E.  F.  of  the  combination, 
and  vice  versa. 

It  seems,  however,  that,  in  view  of  the  fact  that  with  the 
arc  at  ordinary  operating  distance  from  the  rear  condenser 
lens,  the  light  ray  di- 
verges after  passing 
through  the  rear  lens 
(see  A-B,  Plate  1)  and 
that,  incidently,  this 
divergence  increases  with 
increased  focal  length  of 
the  rear  lens,  it  is  ad- 
visable that  the  condens- 
ing lenses  be  placed  as 
close  as  possible  to  each 
other  (without  actual 
mechanical  contact,  which 
latter  would  tend  to  con- 

vey    heat    to    the    front  P^te  2,  Figure  43. 

lens),  since  the  further  apart  the  lenses  are  the  greater  must  be 
the  loss  through  the  aforesaid  divergence  of  the  light  ray. 
A  and  B,  Plate  1,  show  a  6l/z  and  a  7l/2  lens,  with  the  arc 
the  same  distance  from  the  lens,  using  equal  amperage  in 

both  cases.  Even  with 
the  lenses  set  so  that 
their  curved  surfaces  are 
within  one-sixteenth  of 
an  inch  of  each  other 
there  will  still  be  some 
loss,  but  this  cannot  be 
avoided,  since  if  we  pull 
the  arc  back  far  enough 
to  bring  the  light  rays 
parallel  after  passing 
through  the  front  lens, 

Plate  3,  Figure  44.  t^ien   we  w^   encounter 

still  greater  loss  on  the 

arc  side  of  the  lens,  by  reason  of  increased  distance  between 
the  arc  and  the  lens  and  the  law  that  intensity  of  illumination 
decreases  inversely  with  the  square  of  the  distance  from  the 
light  source. 


116 


MOTION    PICTURE   HANDBOOK 


Plates  2  and  3  illustrate  the  relative  loss  through  spacing 
of  the  lenses,  Plate  2  shows  the  lenses  set  with  their  curved 
surfaces  approximately  one-sixteenth  of  an  inch  apart. 
Plate  3  shows  the  lenses  spaced  so  that  their  curved 
surfaces  are  one-half  inch  apart.  It  will  be  observed  that 
the  loss  of  light  is  materially  greater  in  Plate  3  than  in 
Plate  2. 

It  is  also  of  interest  to  note  the  difference  in  the  light 
beam  itself.  In  Plate  2  the  beam  does  not  narrow  down  quite 
so  much  as  it  does  in  Plate  3,  and  the  crossing  point  of  the 


Diagram  showing  how  the  back  focus  and  the  size  of  the  aperture  of  the 
objective  lens  determine  the  distance  between  condensers  and  anerture. 


20        19 


15         14         13         12         II         10          9          8 
Distance  between  condensers  and  aperture  when  the  buck  focus  of 


Plate  4,  Figure  45. 


rays  is  much  nearer  to  the  lens,  which  means  that  the  E.  F. 
of  the  combination  has  been  lengthened  by  spacing  the 
lenses.  However,  due  to  reasons  already  set  forth  I  believe 
it  is  better  practice  to  work  with  a  fixed  E.  F.y  setting  the 
condensing  lenses  so  that  their  curved  surfaces  are  not  more 
than  one-sixteenth  of  an  inch  to  one-eighth  of  an  inch  apart, 
and  make  other  conditions  fit  this  one. 

Never  have  the  lenses  actually  touching  each  other,  since 
mechanical  contact  would  serve  to  impart  considerable  heat 
to  the  front  lens,  which  is  decidedly  undesirable. 


FOR    MANAGERS    AND    OPERATORS 


117 


The  novice  would  probably  say  that,  since  the  light  cone 
is  shorter  in  Plate  3  than  in  Plate  2,  the  E.  F.  of  the  Plate  3 
combination  would  be  less.  The  opposite  is  true,  however, 
Measurement  from  a  point  half  way  between  the  two  lenses 
to  the  point  where  the  rays  begin  to  diverge  from  the  main 
beam  will  show  that  the  cone  is  shorter  in  Plate  2  than  in 
Plate  3. 

It  may  be  stated  as  an  absolute  fact  that  when  the  con- 
denser is  made  up  of  two  factors  of  different  focal  lengths, 
as  for  instance,  a  6l/2  and  a  7l/2  lens,  the  better  practice  is  to 


Showing  how  the 
objective  is  covered 
by  the  incident  light 
when  the  directions 
given  in  the  tables 
are  followed. 


1  



Tmhies-back  focus 
of  objective  lens. 

5 

6 

NOTE.— Line  A  would  pass  from  the  extreme  edge  of 
the  conuenser  to  the  extreme  edge  of  the  objective 
lens  and  just  pass  through  the  narrowest  part  of  the 
machine  aperture.  Line  B  goes  from  the  opposite 
extreme  edge  of  the  condenser  to  the  opposite  extreme 
edge  of  the  objective.  And  while  these  two  rays  form 
an  internal  part  of  the  condenser  beam  of  light  they 
form  the  extreme  rays  of  the  beam  after  passing  the 
aperture. 


place  the  shorter  focal  length  lens  next  the  arc.  This  is 
proven  by  A-B,  Plate  1.  The  only  objection  to  so  doing  is 
that  the  thick  lens  is  more  apt  to  break  than  is  the  thinner 
one,  but  this  may  be  very  largely  if  not  entirely  overcome 
by  the  installation  of  a  modern  condenser  mount,  of  which 
the  Elbert  or  Preddy  (see  index)  are  excellent  examples. 

In  the  course  of  the  aforementioned  experiment's  it  has 
been  proven  to  the  author's  entire  satisfaction  that,  provided 
the  front  lens  of  the  condenser  combination  be  in  line  with 
and  square  with  the  aperture  and  objective,  the  fact  that  the 


118  MOTION   PICTURE   HANDBOOK 

rear  condensing  lens  it  not  exactly  square  or  in  line  with  the 
front  one  does  not  make  any  serious  difference,  provided, 
of  course,  that  the  fault  be  not  too  great.  I  do  not  wish  to 
be  understood  as  saying  that  this  condition  ought  to  be 
allowed  to  obtain.  The  better  practice  is  to  have  the  entire 
lens  system  in  exact  line,  but  with  present  projector  mounts 
this  is  ,a  somewhat  diffcult  thing  to  accomplish,  and  failure 
to  accomplish  the  lining  of  the  two  condenser  factors  per- 
fectly with  each  other  will  not  be  a  very  serious  matter. 

Another  extremely  important  relation  between  the  con- 
densing lens  and  the  objective  is  illustrated  in  Plate  4,  in  which 
A  represents  the  extreme  limit  of  light  from  the  lower 
edge  of  the  condensing  lens  when  it  is  placed  16  inches  from 
the  aperture  of  the  machine.  You  will  observe  that  with 
the  condenser  at  a  distance  from  the  aperture  which  will 
place  the  arc  in  focus  (the  point  where  the  condenser  ray 
begins  to  diverge),  which  is  the  point  where  the  picture  will 
receive  evenly  distributed  illumination,  the  light  will  pass 
through  the  aperture  and  become  a  diverging  beam.  This 
is  clearly  shown  in  Plate  5,  which  shows  the  light  beam  as  in 
actual  projection,  and  is  proven  in  Plate  6,  in  which  the 
condenser  is  covered  by  a  metal  plate  in  which  are  two  holes 
located  diametrically  opposite  each  other  and  about  a  half-inch 
from  the  edge  of  the  lens.  It  will  be  seen  from  Plate  6 
that  the  rays  from  the  outer  edge  of  the  condenser  lens 
actually  do  act  precisely  as  indicated  in  diagram,  Plate  4.  In 
Plate  7  the  same  two  rays  are  passed  on  through  the  ob- 
jective lens. 

From  this  the  inevitable  conclusion  is  reached  that,  with  the 
crater  in  focus  at  the  aperture,  the  closer  the  condenser  is  to  the 
aperture  the  more  rapid  will  be  the  divergence  of  the  beam 
beyond  the  aperture,  though  the  increase  from  this  will  be 
comparativetly  slight.  It  will  also  be  seen  that  the  greater  the 
distance  from  the  aperture  plate  to  the  objective  lens  aperture 
the  wider  the  light  beam  will  be  at  the  point  it  encounters  the 
lens,  See  Plate  8.  It  therefore  is  an  undoubted  fact  that 
the  diameter  of  the  objective  lens  is  an  exceedingly  im- 
portant factor,  particularly  with  long  focal  length  lenses,  and 
it  is  a  factor  which  must  be  taken  into  very  serious  account 
in  the  matching  up  of  projector  lens  systems. 

Plate  9  shows  the  loss  of  light  through  using  a  lens  of 
too  small  diameter.  This  loss  may  be  slight;  or  it  may  be 
very  great.  In  many  cases  it  is  the  latter.  In  this  case  the 
loss  is  far  greater  than  appears,  because  the  camera  only 
caught  the  loss  which  fell  outside  the  lens  barrel,  whereas 


FOR  MANAGERS  AND  OPERATORS 


119 


I 


the   actual    diameter    of    the    lens    aperture    is    considerably 
less  than   the  outside  diameter  of  the  barrel. 

In  Plate  4,  the  long  scale  marks  condenser  distance,  and  the 
short  scale,  to  the  right,  indicates  the  back  focus  of  the 
objective.  Any  objective  lens  may  work  at  any  one  of  several 


120 


MOTION    PICTURE   HANDBOOK 


s 

I 

E 

oT 

D 

rt 


different  distances  from  the  film.  That  is  something  I 
have  never  been  able  to  make  fit  in  with  any  plan  I  could 
evolve  for  matching  up  a  projector  lens  system.  Like  most 
other  things,  however,  once  you  get  hold  of  the  right  key 


FOR    MANAGERS    AND    OPERATORS  121 

it  is  very  simple,  and  the  key  to  this  particular  problem  is 
"back  focus." 

In  matching  up  a  projector  lens  system,  first,  using  the 
well-known  formula  for  finding  the  equivalent  focus  of  the 
lens  required  to  project  the  size  picture  you  want  at  the 
distance  your  condition  calls  for,  determine  the  E.  F.  of 
the  lens  you  want,  procure  it,  mount  it  in  the  machine,  and, 
using  any  condenser,  project  a  picture,  and  very  carefully 
adjust  the  objective  until  the  picture  on  the  scree'n  is  in 
sharp  focus.  Having  done  this,  stick  a  rule  through  the 
aperture  and,  with  its  end  against  the  lens,  measure  the 
exact  distance  of  the  rear  surface  of  the  rear  combination  of 
the  objective  from  the  film  track  surface  on  the  aperture. 

This  measurement  will  be  the  BACK  FOCUS  at  which  your 
lens  will  work,  and  it  is  this  measurement  and  not  the  equiva- 
lent focus,  which  must  be  used  in  matching  up  the  lens 
system.  The  E.  F.  has  absolutely  no  value  whatever  except 
to  enable  the  operator  to  select  the  proper  lens  to  project 
the  size  picture  he  wants  at  the  given  distance. 

At  this  point  we  reach  an  item  of  much  importance,  con- 
cerning w/hich  positive  data  cannot  as  yet  be  given,  viz.: 
The  selection  of  an  objective  lens  of  the  right  diameter  to 
fit  local  conditions.  Excess  in  diameter  is  undesirable,  in 
that  it  is  likely  to  set  up  trouble  in  the  shape  of  travel 
ghost.  Insufficient  diameter,  on  the  other  hand,  means  loss 
of  light,  and  loss  of  light  is  expensive.  On  the  whole,  it  is 
much  better,  I  believe,  to  get  a  lens  of  too  large  than  too 
small  diameter,  because  it  is  an  easy  matter  to  stop  down  the 
large  lens  to  just  the  size  needed,  whereas  the  small  diameter 
cannot  possibly  be  made  larger. 

On  the  whole,  I  think  the  best  recommendation  we  can 
make  at  present  is  that  the  E.  F.  of  the  required  lens  be 
found,  and  that  a  lens  be  ordered  having  a  diameter  equal 
to  one-half  its  E.  F.,  up  to  4^  inches  E.  F.,  the  diameter  beyond 
that  focal  length  to  remain  fixed  at  2%  inches,  up  to  7  inches 
E.  F.,  beyond  which  it  might  possibly  be  increased  to  2^  inches 
with  advantage.  When  the  lens  is  received,  place  it  in  the 
machine  and  focus  the  picture  sharply  on  the  screen,  then  measure 
the  back  focus,  as  already  directed,  and  remove  the  lens.  Now 
place  a  sheet  of  white  paper  inside  the  mechanism  in  the  exact 
position  occupied  by  the  back  surface  of  the  lens,  supporting 
it  in  any  convenient  way,  without  Jiaving  changed  the  position 
of  the  lamp  with  relation  to  the  condenser  or  of  the  lamp- 
house  with  relation  to  the  aperture,  strike  an  arc,  and  measure 


122 


MOTION   PICTURE   HANDBOOK 


the  light  on  the  paper.  If  the  lens  meas- 
ures 2  inches  in  diameter  and  the  light 
measures  2  inches  across,  all  is  well.  If 
the  light  measures  more  than  2  inches 
across,  but  only  2  inches  up  and  down,  the 
lens  still  will  do  fairly  well,  though  there 
will  be  some  loss.  If,  however,  the  lens 
measures  greater  than  the  light,  stop  the 
lens  down  to  the  diameter  of  the  light  at  both 
ends,  by  means  of  rings  of  metal  in  which 
you  have  made  a  circular  opening  of  proper 
size.  I  do  not  pretend  to  say  that  this 
advice  is  perfect.  It  is,  however,  the  best  I 
can  offer  at  this  time,  and  is,  I  am  sure, 
based  on  the  right  idea. 

A  Digression.  Let  me  pause  here,  for 
T-;  want  of  a  more  fitting  place,  and  digress 
^J  for  a  moment  to  show  you  an  interesting 
£  light  ray  picture. 

.£?      In   Plate   10  we   see   a  condenser  with   a 
^  metal  plate  having  a  number  of  holes,  each 
£f  about   one-quarter  inch  in  diameter.     This 
o  picture  has  no  considerable  value,  except  to 
£  allow  the  operator  or  student  to  trace  the 
^  light  ray  action  on  both   sides  of  the  ob- 
jective.    It   will   be  noted  that   the  screen 
illumination   is  not   complete,   especially   at 
the  outer  edges  where  there  were  but  few 
holes  in  the  metal  plate.     Another  interest- 
ing  point  in   this   picture   is   the    circle   of 
light  on  the  back  side  of  the  aperture  plate, 
showing  the  loss  of  light  through  reflection 
from  the  polished  surface  of  the  lens.     In 
fact,   there  are  a  number  of  things  in  this 
photograph   that  will  interest  the  student- 
operator. 

Spherical  Aberration. — An  examination 
into  the  effect  of  spherical  aberration  points 
to  the  fact  that  it  operates  mainly  to  cause 
impurity  of  the  light,  by  reason  of  the  fact 
that  those  rays  which  draw  in  toward  the 
center  earliest  must  naturally  reach  somewhat  into  the  center 
of  the  spot,  and  coming,  as  they  do,  from  the  outer  edge  of 
the  lens,  they  carry  with  them  considerable  color. 


FOR   MANAGERS   AND   OPERATORS 


123 


This,  so  far  as  I  am  able  to  determine,  is  the  principal 
practical  effect  of  spherical  aberration.  It  amounts  to  a  dis- 
coloration of  the  light,  and  hence  a  diminution  of  its  brilliancy, 
though  it  may  or  may  not  be  sufficient  to  be  perceptible  to 
the  eye  in  individual  cases. 

Also  spherical  aberration,  if  excessive,  will  cause  the  spot 
at  the  aperture  to  consist  of  a  series  of  circles  of  light  in- 
stead of  an  evenly  illuminated  field,  and  as  this  plane  is 
refocused  at  the  screen,  there  will,  if  there  is  an  absence  of 
rays  at  the  center,  be  a  dark  spot  or  "ghost,"  or  if  more  of 
the  rays  are  reaching  the  center  of  the  spot  than  its  edges, 
high  lights  will  result.  This  is  usually  the  result  of  the  film 
cutting  the  beam  of  light  too  far  from  the  actual  mean  focus 
of  the  crater,  but  there  are,  nevertheless,  other  conditions 
which  result  in  high  lights  and  shadows  on  the  screen,  and 
spherical  aberration  may  result  only  in  uneven  illumination. 
There  is  practically  no  bad  effect  from  spherical  aberration 
through  the  stereopticon  because  the  rays  reach  the  slide 
before  they  are  displaced,  but  chromatic  aberration  will  show 
if  the  rays  from  the  outer  edges/  of  the  condenser  pass 
through  the  slide. 

Chromatic  Aberration  of  the  Condenser  Beam. — In  Plate  11, 
a  crater  is  constructed  by  cutting  an  aperture  in  a  piece  of 
cardboard  and  placing  a  |  ^CARDBOARD 

piece    of    ground   glass  K      I/MNHOU- 

behind  it.  Back  of  this 
is  placed  a  100  C.  P. 
incandescent  lamp.  The  nLAMENT 
crater  and  screen  are 
placed  at  conjugate  foci 
of  the  condensers.  The 
screen  corresponds  to 
the  aperture  plate  of  the  Plate  11,  Figure  52. 

machine.     A  piece   of   cardboard  pierced  with   a  pinhole   is 
placed  as  shown  in  Plate  11. 

The  results  as  observed  upon  the  screen,  Plate  11,  are:  the 
crater  is  focused  in  full  definition  on  the  screen,  but  it  is 
colored  with  the  shades  of  the  spectrum  in  the  manner  shown. 
Now  it  has  been  demonstrated  by  the  Kinemacolor  process 
that  all  the  colors  of  the  spectrum  can  be  reduced  to  ap- 
proximately two  shades,  viz:  a  reddish-orange  and  blueish- 
green,  which  for  the  sake  of  clearness  we  will  call  orange 
and  green. 

In  Plate  11 A  are  shown  the  same  conditions  described  in 
connection  with  Fig.  1,  except  that  the  colors  of  the  spectrum 


124 


MOTION    PICTURE    HANDBOOK 


have  been  reduced  to  the  two  primary  shades,  viz:  orange 
and  green.  Notice  that  at  the  screen  (or  aperture)  the 
colored  rays  combine  and  form  white  light. 

Now,  if  the  process  shown  in  Plate  11A  be  continued,  and 
a  very  large  number  of  rays  be  drawn,  using  orange  and 
green  ink,  the  result  will  appear  as  shown  in  Plate  11B,  in 
which  it  is  observed  that  the  beam  is  inclosed  by  an  orange 
envelope,  Which  is  thickest  toward  the  central  part  of  the 
beam  and  comes  to  a 
point  or  disappears  en- 
tirely at  the  aperture 
and  the  condenser.  The  ^ 
beam  has  a  core  in  the 
center  which  is  com- 
posed ofi  the  violet,  :,.../?&xr  v  j,  N  ncys. 
blue,  and  green  shades 
of  the  spectrum.  The 
white  part  of  the  beam 
is  caused  by  the  mixture  of  the  two  other  primary  shades,  but 
the  mixture  is  not  perfect  at  all  positions.  At  the  section  AA, 
Plate  11B,  the  white  light  is  most  pure,  but  as  it  approaches  the 
position  of  section  BB,  the  colors  at  the  violet  end  of  the  spec- 
trum commence  to  predominate,  so  that  at  section  BB,  the  white 
zone  has  changed  to  a  dirty  purple.  In<  view  of  this  condition  it 
is  not  difficult  to  understand  why  a  ghost  appears  in  the 
screen  when  the  aperture  is  brought  back  too  far  toward 
point  BB.  When  properly  located  all  the  colors  of  the  beam 
finally  combine  at  the  .aperture  to  form  pure  white  light,  and 
since  it  passes  from  .aperture  to  objective,  all  light  beyond 
the  aperture  is  pure  white.  It  is  also  noted  that  the  light  at 
section  AA,  Plate  11B,  is  pure  white. 


Plate  11A,  Figure  53. 


Plate  11B,  Figure  54. 

Now  it  must  be  remembered  that  the  results  shown  in 
Plate  11B  can  only  be  approximately  true,  since  all  the  colors 
of  the  spectrum,  which  are  infinite  in  number,  have  been 
reduced  to  only  two  shades.  Even  if  only  seven  colors  had 
been  used  in  the  drawing,  the  straight  lines  in  Plate  11B 


FOR   MANAGERS    AND    OPERATORS  125 

would  show  as  curves,  and  more  closely 
resemble  the  true  shape  of  the  actual 
beam.  Nevertheless,  when  a  small  screen 
is  placed  at  different  sections  of  the  actual 
beam,  the  results  show  a  very  close  agree- 
ment with  the  theories  set  forth. 

In  photographing  the  beam,  only  the 
white  and  green  zones  are  actinic  and 
show  in  the  photograph,  and  by  observing 
Plate  11B,  it  is  seen  that  the  theoretical 
shape  of  the  combined  white  and  green 
zones  agrees  very  closely  with  the  photo- 
graph. But  even  to  the  eye  the  beam  has 
a  curved  shape,  which  is  probably  due  to 
the  existence  of  infra  red  at  the  outer 
edge  of  the  orange  envelope. 

It  is  finally  seen,  as  a  further  point  in 
practical  application,  that  one  of  the  im- 
portant functions  of  having  the  crater  in  true 
focus  at  the  aperture  is  to  purify  the  light 
and  avoid  color  effects.  The  aperture  may 
be  placed  a  little  forward  of  the  focal  plane, 
|^  but  should  never  be  behind  it. 

Some  of  the  practical  effects  of  chro- 
matic aberration  are  seen  in  Plate  11C.  It 
will  be  observed  that  whereas  the  holes  in 
the  metal  shield  covering  the  condenser 
are  of  equal  size  the  lower  ray  is  much 
the  stronger.  This  is  partly  due  to  its 
position,  but  also  to  a  very  considerable 
extent  to  color  in  the  upper  ray  which 
reduces  its  actinic  effect  on  the  photo- 
graphic plate. 

Another  important  point  in  connection 
with  the  condenser/is  loss  of  light  through 
poorly  polished,  unevenly  finished  surfaces, 
and  through  discoloration/  of  the  glass. 
Of  late  there  have  been  those  who  have 
advocated  the  addition  of  yellow  to  the 
condenser  lens  glass,  with  the  idea  of  mel- 
lowing light.  With  this  I  cannot  agree. 
I  think  it  is  hardly  necessary  to  enter  into 
a  discussion  of  the  matter,  and  most  emphatically  advise 
operators  to  avoid  the  use  of  lenses  containing  discoloration 
of  any  kind.  In  selecting  a  condenser  lens  first  examine  its 


126 


MOTION   PICTURE   HANDBOOK 


surface,  and,  unless  it  presents  a  perfectly  smooth,  polished 
appearance,  and  evidence  of  having  been  ground  to  the  true 
surface,  reject  the  lens.  In  order  to  perform  its  function 
properly  a  lens  must  be  a  perfect  segment  of  the  surface  of  a 
sphere,  and  this  perfect  shape  can  only  be  obtained  by  grinding. 


k 


A 


B 


Plate  12,  Figure  56. 

It  cannot,   by   any   stretch    of    imagination,   be    had   by   merely 
polishing  the  surface  of  a  molded  lens. 

Stop  .and  consider  the  matter  for  a  moment.  In  order 
to  secure  even  approximately  perfect  results  in  illumination 
at  the  spot  it  is  necessary  that  all  light  rays  emanating 


FOR   MANAGERS   AND   OPERATORS  127 

from  any  point  on  the  crater  and  falling  upon  any  point  on 
the  surface  of  the  lens  be  so  refracted  that  they  will  reach 
the  same  point  in  or  on  the  spot. 

Now  this  can  only  be  accomplished  by  a  perfectly  true  lens 
surface,  and  it  therefore  follows  that  if  the  surface  of  the 
lens  be  not  perfectly  true,  some  of  the  rays  are  going  to 
be  refracted  properly  and  some  are  not,  and  this  of  necessity 
means  loss  in  effectiveness.  With  this  in  view  I  would  call 
the  attention  of  theatre  managers  to  the  fact  that  the  cheap, 
molded  condenser  lenses,  having  an  uneven,  wavy  surface, 
may  be  cheap  in  first  cost,  but  are  a  mighty  expensive  article 
in  the  long  run,  because  of  the  fact  that,  since  it  takes  current 
to  produce  light,  and  you  have  to  buy  the  current,  anything 
which  makes  for  ineffectiveness  in  illumination  means  a 
waste  of  current,  hence  you  are  simply  saving  a  small  sum 
of  money  in  the  original  cost  when  you  buy  a  cheap  condenser 
lens,  and  are  paying  out  money  every  minute  you  run  for 
current  to  produce  light  which  the  cheap  lens  is  wasting. 

Also  reject  any  lens  which  does  not  measure  exactly  4^2  inches 
in  diameter  and  which  has  an  excessively  thick  edge.  Con- 
denser lenses  should  be  exactly  4J^  inches  in  diameter,  and 
should  come  down  to  an  edge  but  little  if  any  thicker  than 
one-sixteenth  of  an  inch.  A  thick  edge  means  unnecessary 
glass;  therefore  unnecessary  absorption  of  light.  In  Plate  12 
A  shows  the  wrong  and  B  the  right  lens  edge.  It  is  im- 
portant that  the  edges  of  condenser  lenses  be  of  standard 
thickness,  .and  that  their  diameters  be  exactly  4H  inches, 
because  not  only  is  excessive  glass  wasteful  (it  is  impossible 
for  manufacturing  reasons  to  bring  the  edge  right  down 
to  a  thin  edge  at  a  4^2  inch  diameter)  but  with  edges  of 
varying  thickness  it  is  impossible  to  make  the  lenses  fit 
properly  in  many  of  the  machine  lens  holders;  also  any 
change  in  diameter  alters  the  fit  of  the  lens  in  the  holder, 
and  these  variations  will  render  it  practically  impossible  for 
the  operator  to  properly  line  up  his  lens  system.  I  would  sug- 
gest that  operators  pay  careful  attention  to  this  matter  be- 
cause lens  manufacturers  seem  to  think  that  "near  or  about" 
is  good  enough,  both  in  diameters  and  lens  edge  thickness. 
They  will  only  change  that  attitude  and  come  down  to  a 
fixed  standard  when  a  large  number  -of  kicks  are  registered 
by  purchasers.  I  have  pointed  out  the  reasons  why  diameters 
and  lens  edge  thickness  should  be  absolutely  standard.  I 
think  you  will  have  no  trouble  in  recognizing  the  fact  that 
these  reasons  are  sound.  It  is  now  up  to  you  to  compel 
lens  manufacturers  to  produce  a  standard  article,  and  I 


128  MOTION    PICTURE   HANDBOOK 

suggest  that  you  insist  on  an  exact  4l/2  inch  diameter  and  a 
lens  edge  thickness  exactly  one-sixteenth  of  an  inch.  It 
is  quite  true  that  to  thus  standardize  lenses  might  add 
somewhat  to  their  cost,  but  even  so,  it  will  be  money  saved 
in  the  end,  no  matter  from  what  angle  the  proposition  be 
viewed. 

In  selecting  your  condensing  lens,  first  examine  its  surface, 
and  if  it  is  not  perfectly  smooth  and  highly  polished  it  is  not 
a  good  lens.  Next  look  through  the  lens  edgewise,  and  if  it  does 
not  show  clear  (has  any  trace  of  color  when  looked  through 
that  way)  reject  it.  It  is  not  a  good  lens. 

If  you  have  any  doubt  whatever  as  to  the  inadvisability  of 
using  lenses  containing  color,  either  purple,  greenish  or  yel- 
low, break  a  clear  white  condensing  lens  in  half;  also  break 
a  lens  containing  discoloration  in  half,  put  these  two  halves 
in  as  the  front  lens  of  your  condenser  combination,  being 
certain  the  rear  lens  contains  no  color,  and  project  the  clear 
light  on  the  screen  through  the  stereopticon  lens.  I  think  the 
appearance  of  the  screen  will  satisfy  you  thoroughly  as  to  the 
advisability  of  rejecting  any  lenses  containing  any  color  what- 
ever. This  experiment  should  only  be  tried  through  the  stereo 
lens,  with  which  the  two  halves  can  be  focused  at  the  screen. 

In  a  camera  the  lens  receives  rays  directly  from  an  object 
and  delivers  them  directly  to  the  screen  (plate). 

In  the  projector  there  are  two  absolutely  separate  lens 
systems,  one  of  which  receives  its  rays  from  the  other,  and 
one  of  our  problems  is  to  so  join  these  two  systems  that  the 
film  picture  will  not  only  receive  a  maximum  of  illumination, 
but  also  that  that  illumination  shall  be  evenly  distributed  over 
the  entire  area  of  the  photograph,  and  that  the  second  or 
objective  system  be  enabled  to  pick  up  the  light  rays  delivered 
to  it  by  the  first  or  condenser  system,  with  the  least  possible 
amount  of  loss. 

Now  these  various  propositions  look  reasonably  simple,  but 
there  are,  in  fact,  some  very  intricate  problems  involved. 
With  relation  to  the  condenser  system,  there  is  one  point 
on  which  we  have  very  little  accurate  data,  viz.:  the  exact 
diameter  of  the  crater  for  a  given  amperage.  Until  this 
matter  is  accurately  determined  our  efforts  in  that  direction 
can  only  be  approximately  correct,  and  possibly  there  may 
always  be  some  differences  in  this  item  since  doubtless  differ- 
ent carbons  will  slightly  alter  crater  size  for  a  given  am- 
perage. 

One  exceedingly  important  point,  which  must  be  borne  care- 
fully in  mind,  is  that  when  the  source  of  illumination  is  greater 


FOR   MANAGERS    AND   OPERATORS  129 

than  a  point  the  light  ray  from  the  condenser  can  never  be 
brought  to  a  point,  for  example :  Assuming  the  crater  to  be 
an  object,  and  the  spot  on  the  aperture  an  image  (which  is 
the  exact  condition),  if  the  crater  be  4  inches  from  the  apex 
of  the  curved  surface  of  the  back  condenser,  and  the  spot  on 
the  aperture  16  inches  from  the  apex  of  the  curved  surface 
of  the  front  condenser,  then  the  diameter  of  the  spot  on  the 
aperture  will  be  four  times  the  diameter  of  the  crater,  of 
which  the  spot  is  an  image,  and  the  spot  will  be  the  nar- 
rowest part  of  the  condenser  beam,  since  at  this  point  the 
beam  will  begin  to  diverge,  therefore  we  cannot  consider  the 
condenser  beam  as  coming  to  a  point  further  on,  as  it  has 
always  been  supposed  to  do. 

Not  only  have  we  discovered  the  fact  that  there  is  a  direct 
ratio  between  the  diameter  of  the  crater  and  the  diameter  of 
the  spot  on  the  cooling  plate,  but  we  have  also  found  that  in 
order  to  obtain  the  most  even  illumination  of  the  entire  aper- 
ture it  is  necessary  that  the  crater  be  "in  focus"  at  the  aperture 
of  the  machine,  or  in  other  words,  that  the  crater  and  spot  be  at 
the  respective  points  of  conjugate  foci  of  the  condenser  lens. 

Now  in  order  to  understand  this  some  of  you  must  do  a 
little  studying.  Take  a  condenser  lens  and  hold  it  near  the 
wall  of  a  room,  opposite  an  open  window,  and  you  will  find 
that  with  the  lens  at  a  certain  distance  from  the  wall  you 
get  a  fairly  good  image  or  picture  of  the  scene  out  of  doors 
on  the  wall.  This  means  that  the  lens  is  at  a  distance  from 
the  wall  equal  to  its  focal  length,  or,  in  other  words,  in  a  posi- 
tion where  rays  emanating  from  a  point  on  an  object  are 
brought  to  a  focus  in  the  image,  not  where  the  light  beam, 
as  a  whole,  is  brought  to  a  point,  which  it  never  is.  Move 
the  lens  further  from  the  wall  and  the  ray  increases  in  size 
and  is  quickly  lost. 

Some  may  dispute  this,  and  cite  the  burning  glass  in  proof. 
Well,  the  point  to  which  the  burning  glass  apparently  brings 
the  rays  is  not  a  point  at  all,  but  merely  an  exceedingly  small 
image  of  the  sun. 

Now,  taking  the  condenser  as  a  whole,  the  crater  of  the 
carbon  takes  the  place  of  the  scene  out  of  doors,  and  the 
aperture  of  the  machine  the  place  of  the  wall.  Of  course 
the  image  is  formed  much  further  away  than  was  the  case 
with  the  lens  held  near  the  wall,  but  this  is  by  reason  of 
the  fact  that  the  crater  (object)  is  close  to  the  lens,  whereas 
the  out-of-door  scene  was  far  away.  If  a  single  lens  were 
used,  instead  of  a  double  one,  these  distances  would  again 
be  altered. 


130  MOTION    PICTURE   HANDBOOK 

And  now  the  question  comes:  When  is  the  crater  in  focus 
at  the  aperture?  This  is  a  somewhat  complicated  proposition, 
in  which  we  must  take  into  consideration  the  known  fact 
that  spherical  aberration  exists  in  the  condenser  system, 
and  the  further  fact  that  the  crater  does  not  set  parallel  to 
either  the  condensing  lens  or  the  film;  therefore,  due  to  the 
latter  equation,  there  is  bound  to  be  precisely  the  same  effect 
at  the  spot  as  there  is  when  the  machine  sets  at  an  angle 
to  the  screen.  In  other  words,  since  the  surface  of  the  crater 
is  not  parallel  to  the  lens  the  whole  crater  cannot  possibly 
be  put  in  sharp  focus  at  the  aperture,  or  anywhere  else.  We 
must  therefore  adopt  a  "mean  focus  point"  or  point  of  actual 
mean  focus,  since  we  cannot  expect  to  get  a  sharp  focus  of 
the  entire  crater  for  reasons  already  pointed  out.  The  point 
of  actual  focus  must,  due  to  spherical  aberration,  be  beyond 
the  plane  where  the  rays  from  the  outer  edges  of  the  spot 
would  naturally  focus,  they  being  focused  nearer  the  lens 
than  the  rays  forming  the  center  of  the  spot;  therefore  the 
plane  of  actual  mean  focus  will  to  some  extent  have  the 
appearance  of  back  focus  at  the  cooling  plate.  In  fact,  the  focus 
of  the  crater  may  be  assumed  to  occupy  any  position  between 
the  circle  of  least  confusion,  which  may  be  recognized  as  a 
round  spot  with  reasonably  sharply  denned  edges,  and  a 
plane  a  few  inches  in  front  of  the  circle  of  least  confusion, 
which  latter  may  be  recognized  as  a  white  spot  surrounded 
by  a  bright  blue  outline.  This  blue  spot  consists  of  the 
aberrated  rays  on  the  back  focus,  the  white  spot  in  the 
center  of  the  haze  being  the  image  of  the  crater. 

The  ordinary  practice  of  the  operator  is  to  carry  a  sharp, 
round  spot  at  the  cooling  plate,  rather  than  the  actual  focus 
of  the  crater,  and  so  long  as  he  can  maintain  this  spot  small 
enough,  and  still  keep  'his  arc  near  enough  to  the  back  con- 
denser to  give  good  illumination,  all  is  well — provided  he  can 
also  maintain  a  distance  sufficiently  great  between  the  con- 
denser and  aperture  to  prevent  the  rays  in  front  of  the 
aperture  from  diverging  beyond  the  limits  of  the  objective 
lens.  See  Plate  8. 

When  the  distance  between  the  condensers  and  film  be- 
comes too  great  to  maintain  a  suitable  size  focused  spot  at 
the  aperture  and  still  keep  the  arc  near  enough  to  the  con- 
denser, the  only  alternative  is  to  focus  the  actual  image 
of  the  crater,  which  is  surrounded  by  a  blue  haze,  at  the 
aperture,  and  in  order  to  do  this  it  is  necessary  to  utilize 
the  whole  length  of  the  machine  table,  and  also  the  shortest 
focal  length  condensers  usually  carried  in  stock,  viz:  two 


FOR  MANAGERS  AND  OPERATORS 


131 


6H  inch,  in  order  that  the  white  center  be  sufficiently  magni- 
fied to  fully  cover  the  aperture.  The  spot  produced  by  this 
arrangement  will  not  look  very  picturesque  on  the  cooling 
plate,  but  will  give  very  superior  results  on  the  screen.  If  the 
amperage  be  very  heavy  it  may  be  necessary  to  use  one 
6l/2  and  one  7l/2  condenser,  or  if  very  light  then  one  5^  and 
one  6l/2  will  be  best.  In  this  we  assume  the  limit  of  the 
machine  table  to  be  such  that  approximately  twenty-two 
inches  can  be  had  between  the  condensers  and  aperture. 

Note.— You  cannot  have  too  great  a  distance  between  the 
condensers  and  aperture,  provided  you  keep  your  arc  near 
enough  to  the  back  condenser. 

The  tables  given  in  this  article  merely  provide  the  mini- 
mum, and  the  condensers  therein  named  are  for  working 
w^;h  the  spot  at  the  plane  of  least  confusion  only.  I  would 
suggest  that  any  condition  calling  for  greater  focal  length 

condensers  than  6^2  and 
iy-2  will  be  better  taken 
care  of  by  using  the 
spot  with  the  blue  haze 
and  shorter  condensers 
and  the  limit  of  dis- 
tance between  the  con- 
denser and  film. 

Remember  this:  The 
spot  itself  is  actually  an 
image  or  picture  of  the 
crater.  It  therefore  fol- 
lows that  any  attempt  to 
use  both  craters  with 
A.  C.  will  set  up  diffi- 
culty, since  it  will,  in 
the  very  nature  of 

things,  be  extremely  difficult,  if  not  impossible,  to  get  their 
images  properly  superimposed  upon  each  other. 

Some  operators  have  got  splendid  results  from  meniscus- 
bi-convex  condensers,  whereas  others  have  reported  no  per- 
ceptible advantage  in  their  use.  It  is  all  a  matter  of  local 
conditions.  Operators  who  have  difficulty  in  getting  their 
arc  near  enough  to  the  condenser  are  the  ones  who  will  get 
best  results  with  the  meniscus-convex  combination,  by  reason 
of  the  fact  that  they  gain  at  least  Y^  of  an  inch  between  the 
arc  and  the  condenser,  owing  to  the  fact  that  the  planes  from 
which  the  conjugate  foci  are  measured  are  changed — that  is 
to  say,  they  are  not  the  same  with  the  meniscus-bi-convex  as 


Plate  13,  Figure  57. 


132 


MOTION    PICTURE   HANDBOOK 


they  are  with  two  plano-convex  (see  Plate  13).  This 
is  owing  to  the  introduction  of  two  more  curved  surfaces. 
The  result  is  less  enlarge- 
ment of  the  crater.  On  the 
other  hand,  the  operator  who 
can  get  near  the  condenser 
with  his  arc  and  still  have  a 
small  spot  will  find  but  little 
benefit  in  the  use  of  the 
meniscus-bi-convex  set,  pro- 
vided the  meniscus-bi-convex 
and  plano-convex  lenses  be 
of  the  same  quality,  except  in 
reduction  of  spherical  aber- 
ration. 

The  theory  upon  which  the 
action  of  light  rays  through 
the  projector  system,  as  set 
forth  in  this  article,  is  based, 
is  a  difficult  matter  to  ex- 
plain in  such  way  that  the 
reader  or  student  will  grasp 
the  idea.  Light  action  is  one 
of  the  most  difficult  things 
imaginable  to  describe  intel- 
ligently by  reason  of  the  fact 
that  in  drawing  diagrams 
representing  light  action  one 
is  limited  to  the  examination 
of  the  action  of  one,  two  or 
possibly  a  dozen  rays  out  of 
literally  millions  and,  as  a 
general  rule,  the  student  has 
difficulty  in  considering  the 
single  ray  or  the  few  rays 
shown  in  the  diagram  as 
being  representative  of  the 
action  of  countless  numbers 
of  rays  which  accompany  it 
but  are  not  shown. 
'  In  this  connection,  as  a  di- 
gression, it  might  be  interesting 
to  know  that  scientists  tell 
us  that  a  bundle  of  thirty-six  Plate  14,  Figure  58. 


FOR   MANAGERS    AND    OPERATORS  133 

light   rays   will   have   approximately   the   same    area  as   that 
of  a  single  human  hair. 

Beginning  with  a  fact  with  which  all  are  more  or  less 
familiar,  viz.:  that  from  each  point  in  a  light  source  rays 
radiate  in  all  directions  (in  the  case  of  a  projection  arc  light 
crater  it  would  not  be  literally  in  "all  directions,"  but  in  all 
directions  over  an  area  covering  what  would  be  practically 
equal  to  one-half  the  surface  of  a  globe)  until  they  meet 
with  some  obstruction.  After  leaving  the  crater  the  first 
obstruction  encountered  is  the  condensing  lens  through  which 
the  rays  must  pass.  This  gives  us  countless  numbers  of 
cones  of  light  as  A-l-2,  B-l-2,  C-l-2,  Plate  14,  each  cone 
having  its  apex  at  a  point  in  the  crater,  and  its  base  on  the 
surface  of  the  condensing  lens.  The  sum  of  these  cones 
represents  the  total  light  passing  through  the  condenser. 
Each  one  of  these  cones  is  made  up  of  diverging  rays  ex- 
clusively, up  to  the  rear  surface  of  the  condensing  lens. 
With;  this  I  believe  we  all  will  agree,  and  thus  endeth  the 
first  part. 

But  when  we  come  to  examine  into  their  action  beyond 
the  rear  surface  of  the  condensing  lens  we  find  that  the  fore- 
going does  not  fully  elucidate  or  make  clear  the  entire  prob- 
lem. 

First:  From  each  point  on  the  crater  we  have  rays  enter- 
ing every  minute  pinpoint  on  the  surface  of  the  condenser, 
therefore  through  each  point  of  the  condenser  we  have  pass- 
ing a  cone  of  converging  rays,  each  cone  carrying  a  complete 
image  of  the  crater,  as  per  A-C-2,  A-C-1,  so  that  we  are  also 
entirely  correct  when  we  consider  the  total  light  passing 
from  the  crater  through  the  condenser  as  consisting  of 
countless  numbers  of  cones  of  converging  rays  having  their 
apex  at  a  point  on  the  condenser  at  1-2,  Plate  14.  It  will 
thus  be  seen  that  while  we  do  not  actually  have  two  sets  of 
rays  we  do  have  a  double  light  action.  It  may  very  reason- 
ably be  asked:  "If  the  first  part  includes  the  total  rays  pass- 
ing from  the  crater  through  the  condenser,  and  the  second 
part  merely  does  the  same  thing  in  a  different  way,  why 
bother  with  the  second  part  at!  all  when  the  action  first 
described  is  more  generally  understood?" 

The  reason  for  analyzing  the  action  of  light  rays  complete- 
ly and  describing  the  second  part  is  because  it  gives  us  a 
clearer  understanding  of  what  follows. 

Now  having  in  mind  one  of  the  cones  A-C-1,  or  A-C-2, 
Plate  14,  it  will  be  readily  seen  that  rays  A-l  and  C-l  meet- 
ing at  a  point  on  the  condenser  will,  even  though  refracted, 


134 


MOTION    PICTURE    HANDBOOK 


cross  at  the  plane  of  the  condenser.  This  can  easily  be 
proven  by  using  a  refractometer.  It  therefore  follows  that 
as  the  total  rays  entering  and  passing  through  the  condenser 
from  the  crater  may  be  considered  as  consisting  of  count- 
less cones  having  their  apex  at  a  point  on  the  condenser,  the 
crossing  point  or  reversal  of  the  image  must,  in  the  very 
nature  of  things,  take  place  at  the  rear  plane  of  the  rear 
condenser  and  at  no  other  place.  Undoubtedly  the  rays  do 
cross  each  other  before  reaching  the  condenser  plane,  but  only 
when  on  their  way  to  and  from  a  point  which  is  receiving  a 
complete  image  of  the  crater. 

This  action  is  perhaps  made  most  clearly  intelligible,  and 
may  be  best  adapted  to  use  in  this  article  by  considering 
cone  A-l-2,  cone  B-l-2,  cone  C-l-2,  cone  A-B-1,  A-B-2  and 
B-C-2  (remembering  that  these  are  but  representative  of 


Plate  15,  Figure  59. 

millions  of  other  similar  cones  at  other  pinpoints  on  the 
crater  and  condenser)  as  being  two  sets  of  rays.  Please 
understand  that  we  do  not  mean  by  this  that  there  actually 
are  two  sets  of  rays,  but  merely  use  that  term  as  a  con- 
venient medium  through  which  to  describe  certain  action  of 
the  light  which  really  is  the  same  group  of  rays  acting  in  two 
different  ways. 

Theory  of  double  action  may  perhaps  be  made  more  un- 
derstandable by  means  of  diagram,  Plate  15,  which  is  a 
diagrammatic  representation  of  pinhole  photography. 

In  Plate  15,  at  A,  we  see  a  diagrammatic  representation  of 
pinhole  photography,  in  which  rays  by  the  millions  go  in 
every  direction  from  every  point  of  arrow  B-C,  but  only  those 


FOR    MANAGERS    AND    OPERATORS  135 

rays  striking  pinhole  D  can  pass  through  and  form  an  image 
on  the  screen  at  E-F.  That  is  the  idea  we  had  in  mind  in 
saying  that  one  set  of  rays  projected  the  whole  crater.  To  get 
the  point  of  view,  you  must  consider  each  minute  point  on  the 
back  plane  of  the  condenser  as  being  a  pinhole,  and  as  a  matter 
of  fact  it  does  act  in  exactly  that  way,  therefore  each  minute 
pinhole  point  of  the  condenser  will  receive  one  ray  from  each 
pinpoint  of  the  crater  and  will  therefore  project  an  image  of 
the  crater,  as  a  whole,  to  the  aperture  of  the  machine.  This 
same  thing  is  shown  photographically  in  Plate  16,  in  which 


Plate  16,  Figure  60. 

A  is  the  machine  aperture,  covered  by  a  plate  in  which  are 
two  pinholes,  and  B  the  back  factor  of  an  objective,  covered 
with  a  plate  containing  one  pinhole.  The  action  is  that  rays 
from  the  lower  half  of  upper  cone  X  pass  through  as  ray  Y, 
whereas  from  the  upper  half  of  cone  X  pass  through  as  ray 
Y.  The  photo  is  a  poor  one,  as  it  is  extremely  difficult  to 
get  a  good  picture  of  such  weak  rays.  A  comparison  will 
reveal  the  fact  that  the  action  in  A,  Plate  15  and  in  Plate  16, 
is  identical. 

The  second  set  of  rays,  viz.:  those  emanating  from  a  point 
on  the  crater,  represented  by  cones  A  1-2,  and  B  1-2,  and  C 
1-2,  Plate  14,  project  to  the  same  aperture,  in  converging 
lines,  rays  from  every  infinitesimal  portion  of  the  crater,  and 
that  is  the  real  explanation. 

The  foregoing  theory  is  not  altogether  coincided  in  by 
some,  but  the  fact,  nevertheless,  remains  that  it  is  the  only 
one  by  means  of  which  we  can  explain  one  phenomenon,  viz.: 
why  the  beam  of  light  is  round  as  it  emerges  from  the  objec- 
tive, and  continues  so  for  a  distance  varying  with  the  focal 
length  of  the  lens,  and  thence  to  the  screen  is  rectangular. 
And  now  comes  the  difficult  part  to  explain. 

In  Plate  14  we  see  a  diagrammatic  representation  of  Grif- 
fiths' theory,  as  applied  to  the  condenser  system.  In  Plate  16 
we  see,  in  photography,  precisely  the  same  thing  as  applied  to 


136 


MOTION    PICTURE    HANDBOOK 


the  objective  lens.  Always  bear  in  mind 
one  fact,  viz.:  the  optical  action  of  the 
objective  lens  and  the  optical  action  of 
the  condensing  lens  is  in  every  respect 
identical. 

Now  to  follow  this  matter  through 
we  will  consider  Plate  17,  which  is  a 
photographic  representation  of  light 
ray  action  in  an  objective  lens,  in 
which  X  is  a  shield  containing  a 
standard  machine  aperture,  covered  by  a 
brass  plate  containing  two  pinholes.  Y 
is  a  standard  projection  lens,  with  one- 
half  of  its  barrel  cut  away,  1  and  2  be- 
ing respectively  the  back  and  front 
factors  of  the  lens,  though  2  is  hidden 
behind  its  container.  This  photograph  is 
made  with  the  aperture  and  the  lens 
in  actually  working  position,  and  with 
the  light  projected  through  the  con- 
denser in  the  ordinary  way,  under 
actual  operating  conditions.  You  will 
observe  that  the  light  coming  through 
the  upper  pinhole,  Plate  17,  diverges 
into  a  cone,  which  corresponds  to 
cone  A,  1-2,  Plate  14.  This  cone  cov- 
ers very  nearly  the  full  aperture  of  the 
lens.  The  light  passing  through  the 
lower  pinhole  does  exactly  the  same 
thing,  and  the  two  cones  begin  to  in- 
termingle at  L,  and  from  there  on  to 
the  lens  a  small  central  light  pyramid 
is  shown,  the  upper  half  of  which  is 
the  upper  edge  of  the  lower  pinhole 
cone,  and  its  lower  edge  the  lower 
edge  of  the  upper  pinhole  cone.  Be- 
yond the  back  factor  of  the  lens,  be- 
tween the  two  lens  factors,  you  can 
easily  trace  the  action.  And  it  is  made 
clear  in  this  photograph  that  the  bend 
which  starts  the  final  crossing  or  trans- 
position of  the  rays  takes  place  at  the 

first  or  back  surface  of  the  first  or  back  combination  of  the 
objective,  even  as  it  takes  place  at  the  back  surface  of  the  rear 
lens,  Plate  14.  The  action,  as  between  the  diagram,  Plate 


FOR    MANAGERS    AND    OPERATORS  137 

£i;y  <i--uii:  «;•-  •••<  '  *•«,::•    •  *     ;!W' 

14,  and  the  photograph,  Plate  17,  is  precisely  identical  in 
every  way.  As  the  light  leaves  the  front  end  of  the  objective 
you  will  observe  that  rays  of  the  two  are  not  entirely  inter- 
mingled but  that  the  mingling  can  be  traced  clear  through 
by  the  brighter  light.  This  intermingling  condition  continues 
out  to  where  the  cone  projected  by  the  upper  pinhole 
has  passed  down  sufficiently  to  entirely  leave  the  cone 
thrown  from  the  lower  pinhole,  which  latter  is  at  the  same 
time  passing  on  its  way  to  the  screen.  The  action  of  these 
two  cones  of  rays  are  typical  of  those  passing  through  every  pin- 
point of  the  film  picture. 

Each  individual  point  of  the  film  acts  as  does  the  pin  hole,  and 
dn  sending  a  cone  of  rays  forward  exactly  like  those  shown  at  L, 
Plate  17,  and,  since  each  of  the  rays  contained  in  each  of  these 
cones  carries  an  image  of  the  point  of  the  film  through  which 
it  passed,  it  follows  that  all  these  rays  must  be  refocused  at 
the  screen;  it  also  follows  that  the  actual  crossing  is  as 
shown  in  the  photograph.  I  believe  this  photograph  will  be  of 
vast  interest  to  operators. 

And  now  let  us  apply  the  theory  of  the  "two  sets  of  rays," 
and  see  how  it  works  in  practice.  Operators  have  long  been 
puzzled  as  to  why  the  spot  on  the  revolving  shutter  is  round 
when  the  shutter  is  close  to  the  lens,  whereas  a  little  further 
ahead,  toward  the  screen,  it  becomes  rectangular.  The 
two-ray  idea  is  the  only  theory  that  seems  to  account  for 
this,  and  it  is  to  some  extent  this  fact  which  has  convinced 
me  of  its  absolutely  correctness. 

First  fix  the  following  firmly  in  your  mind.  There  are  two 
complete  but  entirely  separate  optical  systems  in  the  projec- 
tion machine  lens  system,  which  are,  in  effect,  combined  into 
one.  Remember  that  the  optical  action  of  the  condenser  and 
objective  is  precisely  the  same.  In  fact  the  condenser  is  a  crude, 
extremely  imperfect  objective  lens ;  therefore,  we  have  in  effect 
two  objective  lenses  joined  together,  and  the  object  ds  to  so 
join  these  two  systems  together  that  there  will  be  a  maximum 
of  illumination  of  the  object  to  be  projected,  and  the  rays 
directed  against  and  through  this  object  by  the  first  system 
must  be  so  joined  to  the  second  system  that  there  will  be  a 
minimum  loss  of  light,  and  no  opposition  created  by  the 
refractive  power  of  one  system  as  against  the  refractive 
power  of  the  other  system.  The  second  system  (the  objec- 
tive) picks  up  the  rays  delivered  at  the  aperture  by  the  first 
system  (the  condenser)  exactly  as  they  are  delivered  by  it, 
therefore  when  the  distance  of  the  crater  from  the  rear  con- 
densing lens  is  so  proportioned  with  relation  to  the  distance 


138  MOTION    PICTURE    HANDBOOK 

from  the  back  plane  of  the  rear  condensing  lens  to  the  aper- 
ture that  the  image  of  the  light  source  (the  crater)  is  in 
exact  focus  at  the  aperture,  and  the  spot  is  of  such  size  that 
the  circle  of  clear,  white  light  covers  the  aperture  completely, 
with  sufficient  margin  to  enable  the  operator  to  maintain  a 
clear  field,  then  the  plane  of  light  at  the  aperture,  where  the 
objective  picks  up  its  rays,  contains  the  maximum  illumina- 
tion, and,  moreover,  that  illumination  is  evenly  distributed 
over  the  entire  area  of  the  aperture. 

And  now  let  us  see  how  Griffiths'  two-sets-of-rays  theory 
squares  up  with  what  is  actually  observed  to  take  place  in 
practice.  It  has  always  been  somewhat  of  a  puzzle  to  operators 
why  the  rays  emerging  from  the  objective  lens  do  not  immediately 
diverge  straight  to  the  screen,  instead  of  converging  a  little  and 
then  diverging  (this  is  only  noticeable  when  the  condenser  image 
is  smaller  than  the  aperture  of  the  lens),  and  also  that  they 
have  a  more  or  less  round  form  until  they  reach  the  narrow 
part  of  the  beam,  from  which  plane  the  shape  becomes  rec- 
tangular. For  the  sake  of  convenience  we  will  refer  to  that  set 
of  rays  coming  from  a  point  of  the  crater  as  the  crater  set, 
and  those  coming  from  the  whole -of  the  crater  to  a  point  of 
the  condenser  as  the  condenser  set. 

The  first  point  to  determine  is,  in  what  manner  do  these  two 
sets  of  rays  reach  the  objective  lens,  after  which  we  may 
compare  the  result  that  should  occur  with  these  two  sets  of 
rays  with  what  we  actually  observe  in  practice.  It  has  already 
been  said  that  the  condensers  act  precisely  as  would  a  crude 
objective  lens,  therefore,  the  crater  set,  being  the  diverging  set 
of  rays  emanating  from  a  point  of  the  crater,  must  meet  again 
at  a  point  of  the  crater  image  (spot  of  the  aperture),  and  as 
the  film  is  at  this  plane,  these  rays  pass  through  a  point  of  the 
film  cross  and  again  diverge  to  the  objective  lens.  Thus  our 
crater  set  reaches  the  objective  from  a  point  of  the  film,  and 
their  shape  will  correspond  to  the  shape  of  the  aperture  of  the 
condenser.  If  a  slide  carrier  is  used  the  ray  will,  in  the  very 
nature  of  things,  be  rectangular,  but  if  the  condenser  opening 
be  unobstructed  the  ray  will,  of  course,  be  round. 

Now,  let  us  trace  the  condenser  set  from  the  crater  to  the 
objective  lens.  It  has  already  been  explained  that  each 
point  of  the  condenser  is  receiving  a  ray  from  every  point  of 
the  crater,  so  that  through  each  point  of  the  condenser  a  com- 
plete image  of  the  crater  is  being  projected,  and  as  these  rays 
diverge  from  that  point  to  every  part  of  the  crater  image 
which  they  carry,  they  must  carry  a  full  film  image  to  the 
objective  lens,  arriving  at  the  same  as  a  rectangle  somewhat 


FOR   MANAGERS   AND   OPERATORS  139 

larger  than  the  aperture,  therefore,  the  "condenser  set"  of 
rays  arrive  at  the  objective  carrying  a  full  film  image.  It 
therefore  follows  that  if  a  slide  carrier  be  used,  both  sets  of 
rays  will  arrive  at  the  objective  lens  with  an  over-all  rectang- 
ular outline,  one,  the  crater  set,  having  the  shape  of  the  slide 
carrier,  and  the  other,  the  condenser  set,  having  the  shape  of 
the  film  aperture,  the  condenser  set  carrying  a  full  film  image, 
and  the  crater  set  carrying  the  image  of  a  point  of  the  film. 
Now  these  two  sets  of  rays,  one  emanating,  so  far  as  concerns 
the  objective,  from  a  point  of  the  film  and  the  other  from  a 
point  of  the  condenser,  have  a  different  angle  of  divergence, 
and  must  therefore  be  brought  to  a  focus  at  two  different  planes. 
Those  coming  from  a  point  of  the  film,  and,  incidentally,  form- 
ing the  crater  image,  must  focus  at  the  film  image,  viz:  at  the 
screen,  and  those  coming  from  a  point  of  the  condenser  must 
focus  at  the  point  of  the  condenser  image,  and  as  the  angle 
of  divergence  of  the  condenser  set  of  rays  is  much  narrower 
than  the  angle  of  the  divergence  of  the  crater  set,  it  follows 
that  these  rays  will  meet  (focus)  much  nearer  the  lens  than  the 
other  set.  In  fact  their  focusing  point  will  be  identical  with 
the  position  of  a  photographic  plate  in  a  camera  when  taking 
a  picture  of  an  object  as  far  away  from  the  camera  lens  as 
the  condenser  is  from  the  objective,  the  camera  having  a  lens 
similar  to  the  objective.  And  this  is  exactly  where  we  do  find 
the  condenser  image,  viz:  a  little  further  in  front  of  the  objec- 
tive lens  than  the  back  focus  at  which  it  is  working.  The 
existence  of  the  condenser  image  at  this  position  proves  that 
the  condenser  set  of  rays,  the  existence  of  which  has  met  with 
so  much  opposition,  is  really  the  key  to  the  whole  problem,  be- 
cause the  condenser  set  of  rays  carry  the  full  image  of  the 
film,  and  as  they  come  from  a  point  of  the  condenser  the  film 
image  is  reversed  at  the  condenser  image. 

But,  I  hear  some  one  ask,  if  both  sets  arrive  at  the  objec- 
tive rectangular  in  form  when  the  slide  carrier  is  used,  why 
do  they  emerge  from  the  objective  round  in  form?  .  A  bundle 
of  rays  from  a  point  of  the  center  of  the  condenser  will  arrive 
at  the  objective  lens  as  a  rectangular  a  little  larger  than  the 
aperture,  its  style  varying  with  the  B.  F.  of  the  lens,  but  a 
bundle  from  a  point  near  the  edge  of  the  condenser  will  arrive 
at  the  lens  in  a  different  location,  so  that  only  a  part  of  the 
image  from  this  point  enters  the  objective.  The  sum  total  of 
all  the  rectangles  from  every  point  of  the  condenser  is  a 
rectangle  much  larger  than  the  aperture  of  the  lens,  the  result  is 
that  the  beam,  as  a  whole,  is  trimmed  into  a  round  shape.  But, 
you  may  ask,  if  the  rectangle  has  its  corner  rounded  off,  why 


140  MOTION    PICTURE    HANDBOOK 

does  it  show  rectangular  again  after  passing  the  condenser 
image?  You  will  observe  that  the  rectangle  from  one  point  of 
the  condenser  is  smaller  than  the  rectangle  representing  the 
whole  beam  of  light,  so  that  only  one  corner  is  clipped  off 
by  the  lens,  and  while  this  corner  is  on  the  outside  up  to  the 
condenser  image,  thereafter  it  is  on  the  inside,  and  as  there 
is  a  pyramid  from  each  point  of  the  condenser  image,  the 
defective  corner  is  hidden  by  other  pyramids  from  more  cen- 
tral portions  of  the  condensers  which  are  projecting  perfect 
pyramids. 

This  trimming  process  is  also  applied  to  the  crater  set  of  rays, 
whether  they  are  from  a  rectangular  slide  carrier  or  a  round 
condenser.  No  matter  what  shape  they  are,  each  ray  passes 
through  the  condenser  image  at  a  point  corresponding  to  that 
through  which  it  passed  through  the  condenser;  therefore  the 
two  sets  of  rays  emerge  from  the  lens  converging,  the  crater 
set  carrying  an  image  of  a  point  of  the  film  meeting  at  a  point 
of  the  film  image  at  the  screen,  while  the  condenser  set  meets 
at  a  point  of  the  condenser  image,  and  then  diverge  to  the 
full  screen.  This  is  why  you  can  almost  completely  cut  the 
beam  of  light  at  the  condenser  image  with  the  shutter,  and 
still  have  a  full  image  of  the  aperture  at  the  screen.  So  that  it 
will  be  seen  that  that  much  mooted  question  which  has  been 
cussed  and  discussed  for  lo  these  many  years:  "Where  do  the 
light  rays  cross?"  is  answered  by  saying  that  they  are  crossed 
at  the  image  of  the  condenser  when  projecting  moving  pictures, 
and  in  the  center  of  the  lens  when  the  stereo  lens  is  used,  and 
therefore  the  old  theory  holding  that  the  light  rays  crossed 
in  the  center  of  the  lens  still  is  true  when  speaking  of  lantern 
slide  projection.  The  next  question  is,  if  the  film  image  is 
crossed  and  reversed  at  the  condenser  image :  why  is  the  stereo 
slide  image  not  crossed  there  ?  The  answer  is :  The  film 
photograph  is  being  projected  from  the  crater  image  plane, 
whereas  the  stereo  slide  photograph  is  being  projected  from  the 
condenser  plane,  with  the  result  that  the  rays  from  one  point  of 
the  source  carry  a  full  slide  image  which  crosses  where  the  rays 
meet,  viz:  the  image  of  the  source,  or  crater,  and  as  the  center 
of  the  stereo  lens  is  the  best  location  for  this  plane,  it  is  quite 
true  that  the  rays  cross  in  the  center  of  the  lens  when  projecting 
stereo  slides. 

Matching  the  Lenses. — The  following  tables  have  been 
worked  out  as  a  final  result  of  the  foregoing  theories.  By 
their  use  the  operator  will  be  enabled  to  match  up  his  lens 
system  accurately  and  with  as  great  precision  as  the  limita- 
tions of  present  day  apparatus  will  allow. 


FOR   MANAGERS    AND   OPERATORS 


141 


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Table  1,  Figure  62. 


Decimal  Equivalent.—  1/16  =  .0625  ;  1/8  =  .125;  3/16  =  .1875; 
1/4  =  .25;  5/16  =  .3125;  3/8  =  .375;  7/16  =  .4375;  1/2  =  .5; 
9/16  =  .5625;  5/8  =  .625;  11/16  =  .6875;  3/4  =  .75;  13/16  ==  .8125; 
7/8  =  .875;  15/16  =  .9375. 


142  MOTION    PICTURE   HANDBOOK 

Table  1  is  what  might  be  termed  the  "angle  table."  It 
represents  the  tabulated  results  of  what  is  shown  in  the 
diagram  in  Fig.  4.  In  order  to  apply  this  table  proceed  as 
follows: 

First  measure  the  diameter  of  the  opening  of  the  objective 
lens.  Next,  with  the  picture  in  exact  focus  on  the  screen, 
stick  a  rule  through  the  aperture  of  the  machine  and  place 
it  against  the  back  surface  of  the  back  combination  of  the 
objective  lens,  and  measure  the  exact  distance  from  the  lens 
to  the  film,  or,  in  other  words,  from  the  lens  to  the  surface 
of  the  film  track  on  the  aperture.  This  will  give  you  the 
exact  back  focus  of  the  lens  at  the  position  in  which  it  works. 
This  is  of  the  greatest  importance  because  any  given  lens 
may  work  in  different  positions  under  different  circumstances. 
Having  found  the  measurement  of  the  diameter  of  your  ob- 
jective, and  its  back  focus  when  in  working  position,  proceed 
as  follows : 

In  the  extreme  right-hand  column  find  the  number  most  nearly  cor- 
responding1 to  the  back  focus  at  which  your  lens  is  working.  Opposite 
this  number,  in  the  extreme  left-hand  column  you  will  find  the  smallest 
lens  diameter  permissible  at  that  back  focus,  and  at  the  top  of  the 
right-hand  column  we  see  that  the  condensers  must  be  two  "7%s,"  with 
22  inches  between  the  apex  of  the  front  lens  and  the  film.  For  ex- 
ample: Suppose  the  B.  P.  to  be  4%  and  the-*  lens  diameter  1%  inches. 
At  the  sixteenth  line  down  we  find  4.52  (practically  4%)  in  the  right- 
hand  column,  and  opposite,  in  the  left-hand  column,  1%.  We  therefore 
see  that  1%  is  the  least  permissible  lens  diameter,  and  that  our  lens 
is  unsuitable  to  the  work  in  hand.  Looking  at  the  top  of  the  right- 
hand  ^column  we  see  that  with  the  1%-inch  lens  we  must  have  two  7% 
condensing  lenses  with  not  less  than  22  inches  between  the  apex  of  the 
front  lens  and  the  film.  This  is  the  extreme  condition.  Looking  in 
the  third  column  from  the  right,  however,  one  line  further  down  we 
again  find  4.52  and  discover  that  with  a  lens  1  15/16  inches  in  diam- 
eter we  may  use  two  inches  less  between  condenser  and  film,  though 
two  7%  lenses  are  still  required.  Again  looking,  we  find  4.60  in  the 
fourth,  4.6  in  the  fifth  and  so  on  over  to  the  twelfth  column,  where  we 
find  4.540  In  the  bottom  row  and  see  that  with  a  lens  3  inches  in 
diameter  we  could  use  one  5%  and  one  6%  condenser,  with  11  inches 
from  apex  of  front  lens  to  film — the  extreme  condition  in  the  other 
direction. 

Table  2  shows  relative  distances  of  conjugate  foci  and 
amount  of  enlargement  of  the  image  of  the  object,  the  object 
being  the  crater  or  source  of  light  and  the  image  the  spot  on 
the  aperture. 

Diagram  A,  Plate  13,  shows  the  points  from  which  the  dis- 
tances are  measured  with  piano  convex  combinations. 

Diagram  B,  Plate  13,  shows  the  points  from  which  the  dis- 
tances are  measured  with  a  meniscus-bi-convex  combination. 
With  the  piano  convex  combination  X  equals  the  distance 
from  the  crater  'to  the  curved  surface  of  the  back  condenser, 


FOR   MANAGERS    AND   OPERATORS 


143 


and  Y  equals  the  distance  from  the  curved  surface  of  the 
front  condenser  to  the  aperture. 

With  the  meniscus-bi-convex  combination  X  equals  the  dis- 
tance from  the  crater  to  a  point  l/%  of  an  inch  in  front  of  the 
convex  face  of  the  back  condenser,  and  Y  is  equal  to  the 
distance  from  the  center  of  the  bi-convex  condenser  to  the 
aperture. 

The  essential  difference  between  the  meniscus-bi-convex  and 
the  piano  convex  is  that  there  is  less  enlargement  of  the  spot 
on  the  aperture  with  the  former  when  the  E  F  is  the  same 
in  both  cases. 

The  enlargement  with  both  sets  is  equal  to  distance  Y 
divided  by  distance  X,  both  in  inches. 

When  meniscus-bi-convex  condensers  are  substituted  for 
piano  convex  we  increase  X  by  J^  of  an  inch  and  decrease 
Y  by  the  thickness  of  a  piano  lens,  because  the  center  of  the 
bi-convex  occupies  the  same  position  as  the  plane  of  the 
piano  convex. 

Example. — Piano  convex  R  =  4,  Y  =  16,  therefore  enlarge- 
ment equals  16  -f-  4  =  4  times,  so  that  the  spot  will  be  4  times 
the  diameter  of  the  crater.  Meniscus-bi-convex  X  =  4%$  and 
Y  =  15,  therefore  the  enlargement  equals  15  -f-  4^  =  3.83 
times. 

The  necessary  enlargement  of  the  crater  will  depend  on  the 
number  of  amperes  we  use,  so,  knowing  the  distance  Y,  which 

is  the  distance  the  ob- 

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Table  2,  Figure  63. 


jective  calls  for  between 
the  condenser  and  the 
aperture,  see  table  1, 
we  look  for  that  dis- 
tance under  the  en- 
largement head  we  re- 
quire, but  we  must 
choose  it  in  conjunc- 
tion with  X,  remember- 
ing that  X  is  the  dis- 
tance between  the  crater 
and  the  condenser,  plus 


thickness  of  the  lens,  and  that  with  the  meniscus-bi-convex 
the  enlargement  will  be  less  than  what  the  table  calls  for, 
we  see  the  figures  we  need  will  be  those  giving  slightly  a 
greater  enlargement.  If  with  piano  convex  we  need  a  four 
time  enlargement,  with  meniscus-bi-convex  we  could  choose 
about  a  4j£  time  enlargement.  An  examination  of  the  tables 


144  MOTION    PICTURE   HANDBOOK 

will  make  this  clear,  and  will  show  the  advantage  of  using 
the  meniscus-bi-convex  set  where  it  is  difficult  to  obtain  a 
spot  small  enough  and  still  keep  the  arc  at  proper  distance 
from  the  lens. 

Another  important  point  which  has  been  determined  is  that 
in  thousands  of  instances  objective  lenses  now  in  use  are 
not  large  enough  in  diameter. 

With  reference  to  the  difficulties  that  may  be  encountered 
with  the  large  aperture  lens  and  the  revolving  shutter  the 
following  facts  will  be  of  interest: 

The  diameter  of  the  beam  of  light  at  its  narrowest  part 
in  front  of  the  objective  is  in  proportion  to  the  distances 
between  the  condenser  and  aperture  and  the  equivalent  focus 
of  the  objective  lens.  That  while  it  is  the  equivalent  focus  of 
the  objective  lens  that  determines  where  the  crossing  point 
of  the  rays  in  front  of  the  objective  will  be,  changing  the 
distance  between  condensers  and  aperture  changes  the  diam- 
eter of  the  narrowest  parti  of  the  beam  considerably  and 
also  causes  a  small  change  in  the  position  of  the  narrowest 
part,  which  is  the  image  of  the  condenser  aperture.  In- 
creasing the  distance  between  the  condensers  and  aperture 
decreases  the  thickness  of  the  beam  at  its  narrowest  part, 
and  vice  versa.  So  that  increasing  the  diameter  of  the  ob- 
jective lens,  and  at  the  same  time  shortening  the  distance 
between  condensers  and  aperture,  operates  to  increase  the 
diameter  of  the  beam  at  its  narrowest  point;  but  if  we  in- 
crease the  diameter  of  the  objective  lens  without  altering 
other  conditions,  the  width  of  the  beam  at  its  narrowest  point 
does  not  increase. 

The  crossing  point  of  the  light  beam  will  hardly  be  discern- 
ible when  the  distance  between  condenser  and  aperture  is 
short,  owing  to  the  fact  that  the  image  of  the  condenser  aper- 
ture is  further  from  the  -lens,  and  consequently  larger,  so  that 
rays  to  this  image  do  not  have  to  converge,  therefore  the  whole 
beam  of  light  will  appear  to  diverge  from  the  lens. 

In  this  connection  it  is  interesting  to  note  that  increasing 
the  distance  between  condensers  and  aperture  may  be  used 
to  eliminate  travel  ghost  when  the  shutter  blade  is  too  nar- 
row. The  effect  of  withdrawing  the  lamphouse  from  the 
machine  head  has  the  same  effect  on  the  narrowest  part  of 
the  beam  of  light  as  withdrawing  the  arc  from  the  condenser 
has  on  the  spot  at  the  aperture. 

In  conclusion:  Until  such  times  as  objective  lenses  and  con- 
densers are  brought  up  to  our  requirements  the  following 
points  should  be  observed:  Always  have  the  crater  as  near 


FOR   MANAGERS   AND   OPERATORS  145 

as  possible  to  the  condensers — say  between  3^  and  2*/z 
inches,  according  to  the  amperage  used,  and  always  have  the 
greatest  possible  distance  between  the  condensers  and  aper- 
ture. 

These  two  conditions  in  some  cases  conflict  with  present  ap- 
paratus, therefore,  it  may  be  necessary  to  compromise  between 
the  two.  But  the  compromise  means  loss  in  efficiency. 

For  convenience  in  the  use  of  these  tables  the  decimal 
equivalents  for  fractions  are  given.  I  believe  the  foregoing  is 
reasonably  clear — at  least  sufficiently  so  that  the  table  can  be 
readily  applied  by  the  operator. 

Caution. — In  measuring  the  back  focus  of  your  lens  be  very 
careful  that  the  end  of  your  rule  is  PERFECTLY  CLEAN,  be- 
cause otherwise  it  might  leave  a  faint  mark  on  the  lens  which 
would  injure  the  definition  of  the  picture  on  the  screen. 

These  tables  do  not  appear  very  imposing,  but  you  may 
take  it  from  me  they  represent  a  vast  amount  of  labor.  I 
would  not  presume  to  claim  perfection  for  them.  In  fact  I 
think  it  quite  possible  they  may  be  subject  to  improvement,  but 
I  do  think  they  are  the  first  really  intelligent  step  in  advance, 
in  this  particular  direction,  since  the  projection  optical  system 
was  first  evolved. 

I  believe  a  great  many  operators  are  now  losing  a  large 
percentage  of  their  light  by  reason  of  the  fact  that  the  diam- 
eter of  their  objective  lens  is  too  small  for  the  condition 
under  which  it  works.  You  will  observe,  too,  that  the  smaller 
the  diameter  of  the  lens  the  farther  away  must  the  conden- 
ser be  from  the  aperture,  and  Table  2  will  show  you  that 


Plate  18,  Figure  63A. 

under  certain  conditions  the  arc  will  be  a  great  distance 
from  the  lens,  thus  involving  excessive  light  loss.  If  you 
are  obliged  to  locate  the  arc  more  than  3l/2  inches  from  the 
condenser  in  order  to  have  a  normal  spot  \l/2  inches  in  diam- 


146  MOTION    PICTURE   HANDBOOK 

eter,  and  still  meet  the  conditions  as  per  Table  1,  you  may 
instantly  conclude  that  something  is  wrong,  and  that  some- 
thing most  likely  is  one  of  two  things,  viz.:  wrong  condenser 
focal  length  or  wrong  diameter  of  the  objective.  Table  2  gives 
objectives  up  to  3  inches.  Personally,  I  believe  2^  should  be 
the  limit. 

Plate  18  is  a  photograph  of  light  rays  obtained  by 
placing  a  metal  diaphragm,  containing  in  its  center  a  hole 
one-quarter  inch  in  diameter,  against  the  front  condenser,  so 
that  the  hole  comes  opposite  to  its  center.  You  will  observe  the 
light  ray  conies  down  to  a  fine  point,  and  the  least  diameter  of 
the  ray  indicates  the  point  at  which  the  shutter  should  be  set. 
In  very  long  and  very  short  focal  length  lenses  it  is  impossible 
to  set  the  shutter  at  this  point  because  in  one  instance  it  comes 
inside  the  hood  of  the  lens  barrel  and  in  the  other  it  is  so  far 
away  that  the  shutter  cannot  reach  it.  This  point  may  be  found 
by  using  a  plate  as  in  the  foregoing  and  with  the  machine  gate 
open  blow  smoke  in  the  ray  in  front  of  the  objective,  whereupon 
the  correct  or  at  least  the  best  position  for  the  shutter  can  be 
plainly  seen. 


Some  men  could 
learn  if  they  didn't 
already  know  it  all 


FOR   MANAGERS    AND   OPERATORS  147 


Projection 


PROJECTION  is  a  term  which,  taken  as  a  whole,  involves 
many  things.  As  a  matter  of  fact,  broadly  speaking, 
we  may  say  that  the  whole  motion  picture  industry 
rests  to  a  large  extent  on  projection.  I  base  this  statement 
on  the  fact  that,  no  matter  how  perfect  may  be  the  work  of 
the  producer,  no  matter  how  beautiful  may  be  the  decora- 
tion of  the  theatre,  or  how  excellent  its  appointments,  or 
how  courteous  its  attendants,  or  how  perfect  its  music,  still, 
if  the  projection  of  the  picture  itself  be  inferior  the  whole 
thing  will  necessarily  be  unsatisfactory  and  in  considerable 
measure  second  rate. 

To  put  perfect  projection  on  the  screen,  and  maintain  it 
perfectly  during  even  one  entire  reel,  requires  ability  of  no 
mean  order,  as  well  as  ceaseless  vigilance,  and  some  con- 
siderable degree  of  artistic  sense.  Not  only  must  the  projec- 
tion machine  be  kept  in  perfect  condition,  in  order  that  there 
may  be  no  unnecessary  movement  in  the  picture,  no  breaking 
of  the  film,  or  other  faults  due  to  a  worn  or  badly  adjusted 
mechanism,  but  also  the  light  must  be  pure  white,  brilliant,  and 
distributed  over  the  aperture  with  perfect  evenness,  so  there 
will  be  no  shadow  on  the  screen,  other  than  that  of  the  photog- 
raphy itself,  and  no  discoloration  of  the  light,  except  that  caused 
by  some  fault  in  the  film  itself. 

It  requires  close  study  and  considerable  experience  on  the 
part  of  the  operator  to  be  able  to  determine  accurately  and 
at  a  glance  whether  a  faint  shadow  or  discoloration  of  the 
light  is  due  to  fault  in  the  light  itself  or  to  fault  in  the  film. 
The  operator  who  proposes  to  deliver  perfect  projection 
must  observe  and  compare  closely.  He  must  study  projection 
from  all  points  of  view,  and  above  all  things  must  never 
arrive  at  the  point  where  he  imagines  there  is  nothing  more 
for  him  to  learn.  When  an  operator  arrives  at  that  point 
he;  will  cease  to  advance  in  his  profession.  The  high-class 
operator  who  produces  high-class  results  on  the  screen  can 
seldom  tell  you,  except  in  a  very  general  kind  of  way,  what 
a  film  portrays,  even  after  he  has  run  it  several  times.  His 
whole  attention  will  be  taken  up  in  constantly  watching  for 
faults  in  the  light,  gauging  the  speed  of  the  projector  to  suit 
the  action  in  each  scene  of  the  film,  and  attending  to  other 
things  in  connection  with  his  projection. 


148  MOTION    PICTURE    HANDBOOK 

And  now  at  this  point  let  me  say  a  few  words  to  managers. 
In  the  olden  days,  so  the  Good  Book  says,  Pharaoh  ordered 
his  Hebrew  slaves  to  make  bricks  when  there  was  no  straw. 
The  Hebrews  could  not  do  this,  because,  the  way  bricks 
were  made  in  that  ancient  day,  straw  was  a  necessary  part 
of  the  proceedings.  There  are,  in  this  and  other  countries, 
many  hundreds  or  even  thousands  of  motion  picture  theatre 
managers  who  are  emulating  the  example  of  Pharaoh.  They 
are  ordering  their  operators  to  produce  high-class  results 
on  the  screen  but  failing  to  supply  them  with  the  necessary 
things  with  which  to  do  it — asking  them  to  "make  bricks 
without  straw." 

The  manager  who  expects  his  operator  to  go  up  into  a 
little  6  by  7  unventilated  sweatbox,  containing  an  old  style, 
worn  out  (or  not  worn  out  for  that  matter — old  style  is 
enough)  projection  machine,  and  produce  high-class  results 
on  the  screen,  is  expecting  more  than  he  is  going  to  get.  It 
is  not  in  the  nature  of  things  and  cannot  be  done.  Yet 
many  managers  not  only  do  this,  but  add  insult  to  injury  by 
refusing  to  purchase  necessary  repair  parts,  by  doling  out 
carbons  one  or  two  at  a  time,  and,  in  general,  making  it 
utterly  impossible  for  their  operators  to  do  their  work  in 
creditable  fashion. 

There  is  another  type  of  manager  who  will,  in  the  begin- 
ning, provide  a  fairly  good  operating  room  and  up-to-date 
equipment,  but  having  done  this  much  considers  his  duty  as 
wholly  finished.  These  projectors,  to  his  way  of  thinking,  ought 
to  run  twelve  hours  a  day  for  the  next  six  years  without  even 
so  much  as  a  new  intermittent  sprocket.  He  is  generous  in  his 
advertising,  spares  no  expense  in  film  service,  and  is,  in  fact, 
liberal  in  everything  except  the  matter  of  operating  room  ex- 
pense. Of  course,  it  follows  that,  under  these  conditions,  his 
operator  is  not  going  to  and,  in  fact,  cannot  produce  high -class 
results  on  the  screen. 

These  managers,  too,  frequently  go  even  further  than  this 
in  their  foolishness,  and,  instead  of  employing  the  best  opera- 
tor obtainable,  paying  him  at  least  a  fair  salary,  get  the  very 
cheapest  man  they  can  find.  Any  one  who  can  twist  a  crank, 
splice  a  film  and  get  some  sort  of  a  picture  on  the  screen  is, 
in  their  opinion,  an  operator,  provided  he  is  cheap  enough. 

The  wise  manager,  the  manager  who  succeeds  in  any  large  way, 
is  the  one  who  employs  the  best  operator  he  can  get,  provides 
him  with  decent  working  quarters,  up-to-date  projection  machin- 
ery, and  says:  "Now  see  here,  Mr.  Operator,  within  reason  you 
may  purchase  anything  you  want  in  the  way  of  supplies.  If  I 


FOR   MANAGERS    AND   OPERATORS  149 

catch  you  wasting  you  will  be  promptly  fired.  I  only  look  to 
you  for  one  thing,  and  that  is  results  on  the  screen,  but  it  is  re- 
sults I  want,  not  excuses" 

The  manager  who  takes  this  position  is  entitled  to  results 
on  his  screen,  and  he  is  of  the  type  of  man  who  is  going  to 
get  them,  too. 

But  to  get  back  to  our  subject.  When  the  operator  is  in 
doubt  as  to  whether  some  faint  shadow  or  discoloration  on 
the  screen  is  due  to  the  light,  or  to  some  fault  in  the  film 
itself,  the  matter  may  be  determined  by  shifting  the  lamp 
a  trifle.  If  the  shadow  or  discoloration  remains  unchan'ged 
as  the  lamp  moves,  it  is  due  to  some  inherent  defect  in  the 
film. 

Discoloration  or  shadows  due  to  light  fault  are  detected 
by  observing  white  or  light  colored  objects  in  the  picture. 
A  white  dress,  for  instance,  must  be  pure  white  all  over.  If 
a  woman  is  in  the  foreground  and  the  bottom  of  her  white 
skirt  is  in  any  degree  yellow,  the  rest  being  pure  white,  it 
means  that  your  light  is  in  need  of  instant  adjustment.  Very 
likely  the  arc  is  too  long.  If  the  discoloration  appears  at 
some  other  point  in  the  picture,  it  means  the  same  thing,  viz., 
the  light  requires  adjustment,  assuming,  of  course,  your 
lenses  are  properly  matched,  so  that  you  can  get  a  clear, 
white  screen.  It  is  not  the  purpose  of  this  work  to  tell  the 
operator  each  separate  adjustment  to  make  to  overcome  or 
correct  every  separate  fault.  This  he  must  learn  for  him- 
self, by  experience.  He  is  presumed  to  have  brains.  If  he 
has  not  a  goodly  quota  of  that  highly  desirable  article  he 
has  no  right  place  in  the  operating  room.  Jf  he  has  brains, 
and  uses  them,  he  will  quickly  learn  how  to  adjust  the  light 
to  correct  the  various  faults. 

When  the  operator  is  allowed  to  use  sufficient  current;  is  pro- 
vided zvith  good  carbons  and  the  right  lenses,  there  is  ordinarily 
no  excuse  for  any  shadow  or  discoloration  of  the  light. 

It  may  be  stated  as  a  matter  of  fact  that  with  modern 
films  of  the  best  makes  it  is  quite  possible  to  project  a 
motion  picture  which  will  be  to  all  intents  and  purposes 
absolutely  free  from  movement  and  absolutely  evenly  and 
brilliantly  illuminated.  This,  however,  can  only  be  done  by 
a  high-class  operator  who  has  at  his  command  ample  cur- 
rent, high  grade  carbons,  and  a  carefully  selected,  up-to-date 
projection  machine. 

This,  however,  must  be  qualified  by  the  statement  that 
there  are  only  a  few  makes  of  films  which  are  to  all  intents 
and  purposes  so  mechanically  perfect  in  their  perforations 


150  MOTION    PICTURE   HANDBOOK 

that  even  a  perfect  projector  will  put  them  on  the  screen 
without  some  movement.  In  fact,  there  are  none  so  perfect 
that  there  is  no  movement  at  all,  though  the  European  Pathe 
and  a  few  American  producers  are  now  very  close  to  the 
ideal  in  this  respect. 

Speed  of  Projector. — The  speed  at  which  the  film  is  run  is  a 
matter  deserving  of  the  closest  study  and  attention  on  the  part  of 
the  operator.  There  are  those  who  insist  that  some  overspeeding 
of  the  projection  machine  lends  "snap"  to  the  picture  on  the 
screen.  This  opinion  is  held  by  no  less  person  than  Mr.  S.  L. 
Rothapfel,  manager  of  the  Rialto  Theatre,  New  York  City. 
Also  Mr.  D.  W.  Griffith,  who  produced  that  marvelous  production 
"The  Birth  of  a  Nation,"  holds  that  it  is  desirable  to  overspeed 
the  film.  With  this  view,  however,  I  am  unable  to  agree.  I  take 
the  position  that  the  actors  who  enact  scenes  in  films  are  presumed 
to  know  their  business,  and  to  enact  the  scenes  in  the  best  pos- 
sible way.  If  this  be  true,  then  overspeeding  of  the  projector  com- 
pels the  shadow-actor  to  enact  a  scene  quite  differently  from  the 
way  it  was  done  in  real  life.  Hence  if  the  speeded  shadow  scene  is 
right,  the  real  scene  was  wrongly  enacted,  and  vice  versa.  I  have 
never  yet  been  able  to  see  a  horse,  for  instance,  moving  across  a 
screen  at  a  speed  at  which  no  horse  could  possibly  move  in  real 
life,  and  be  satisfied,  and  I  think  no  one  else  is  really  satisfied  with 
that  sort  of  thing.  I  am  a  firm  believer  in  the  fact  that  an  ex- 
ceedingly important  part  of  the  operator's  work  is  to  carefully 
gauge  the  speed  of  his  projector,  so  that  the  figures  in  the  various 
scenes  will  move  in  an  absolutely  lifelike  manner,  and  this,  when 
you  come  to  think  of  it,  means  a  great  deal.  It  means  that  the 
operator  must  know  exactly  what  "lifelike  manner"  is,  which 
involves  a  close  study  of  many  things. 

Of  course  if  cameramen  always  ran  their  cameras  at  ex- 
actly 60  feet  per  minute,  all  that  would  be  necessary  in 
order  to  reproduce  a  scene  on  the  screen  precisely  the  way 
it  was  acted  would  be  to  run  the  projector  at  60  per  minute. 
As  a  matter  of  fact,  however,  cameramen,  while  they  are 
presumed  to  run  at  exactly  60  a  minute,  don't  do  anything 
of  the  sort.  Suppose  one  cameraman  misjudges  his  speed 
and  runs  at  58,  or  two  feet  under  normal,  whereas  the 
cameraman  taking  the  next  scene  misjudges  his  speed  in 
the  other  direction,  and  runs  at  62.  Now  if  the  projection 
machine  pounds  along  at  60  a  minute,  one  scene  will  be 
run  too  slow  and  the  other  too  fast,  or  if  the  whole  thing  be 
run  at  either  58  or  62,  one  scene  will  be  correct  and  the  other 
very  far  from  right. 


FOR   MANAGERS    AND   OPERATORS  151 

The  operator  who  thinks  that  the  finer  details  of  projection  are 
not  of  sufficient  importance  to  justify  him  in  giving  them  atten- 
tion is  not  and  never  will,  in  my  opinion,  be  a  high-class  man. 

It  is  quite  true  it  usually  is  a  difficult  and  discouraging 
task  for  the  operator  to  secure  recognition  for  high-class 
work.  In  fact,  many  managers'  won't  let  him  deliver  high- 
class  work,  but,  nevertheless,  the  man  who  persistently  and 
consistently  bends  his  energy  to  improving  his  projection 
in  every  possible  way  is,  I  think,  bound  to  win  out  sooner 
or  later.  High  class  work  cannot  but  be  noticed.  It  may  take 
considerable  time;  it  may  be  discouraging,  but  success  will 
come,  and  with  it,  at  least  in  some  degree,  financial  reward. 

Almost  the  same  thing  may  be  said  of  the  manager.  The 
manager  who  employs  a  high-class  operator,  pays  him  an 
adequate  salary,  provides  him  with  good  working  conditions, 
tools  and  supplies,  and  insists  on  high-class  projection,  may 
not  immediately  see  the  benefit.  Nevertheless  the  public  in 
due  course  of  time  will  recognize  the  fact  that  in  a  certain 
theater  they  are  sure  to  see  a  good  picture,  and,  other  things 
being  equal,  they  are  going  to  patronize  that  theater. 

Overspeeding  the  Machine. — Overspeeding  the  machine  is 
a  reprehensible  thing  from  any  and  every  point  of  view.  It 
is  an  all  too  common  fault,  practiced  by  managers  of  theaters 
who  have  no  respect  for  the  property  intrusted  to  their  care 
by  the  film  exchange  and  no  adequate  conception  of  the 
business  of  exhibiting  motion  pictures  or  their  duty  toward 
their  patrons.  There  is  a  certain  type  of  manager  who  seems 
to  have  an  ingrowing  idea  that  the  public  collectively  is  a 
fool;  that  it  would  rather  see  six  reels  put  on  the  screen 
as  a  ridiculous  travesty  on  projection — as  an  absurd  jumping- 
jack  performane,  than  see  five  reels  put  on  the  screen  right. 
They  insist  on  shooting  a  reel  of  film  through  in  less  time 
than  is  required  for  its  proper  projection.  There  are  man- 
agers who  will  talk  to  you  learnedly  about  a  reel  requiring 
"fifteen  minutes,"  or  "eighteen  minutes,"  according  to  their 
individual  ideas.  They  have  no  adequate  knowledge  of  pro- 
jection themselves,  and  don't  understand  the  fact  that,  whereas 
one  reel  cf  film  may  require  only  fifteen  minutes  (nine  reels 
out  of  ten  will  require  more  time  than  that),  another  may 
require  as  much  as  twenty  minutes;  both  fifteen  and  twenty 
being  extremes.  Many  "managers"  insist  on  putting  on  a 
six-reel  program  in  the  time  that  ought  to  be  consumed  by 
five  reels.  Over  on  the  east  side  of  New  York  City  I  have 
actually  seen  one  thousand  feet  of  film  projected  in  considerably 
less  than  ten  minutes. 


152  MOTION    PICTURE   HANDBOOK 

Overspeeding  the  machine  is  an  outrage  on  the  public;  an  out- 
rage on  the  producer;  an  outrage  on  the  film  exchange;  an  out- 
rage on  the  projection  machine  manufacturer,  and  an  outrage  on 
the  operator  himself.  There  is  no  excuse  for  it — absolutely  none 
at  all.  If  the  house  is  full  and  a  crowd  waiting  to  gain  entrance 
it  would  be  far  better  to  cut  out  one  reel  than  to  injure  the  whole 
performance. 

The  operator  is  very  seldom  to  blame  for  this  particular 
thing.  Nine  times  out  of  ten  it  is  the  manager  himself  who 
commits  what  amount  to  a  crime  against  the  business,  when 
he  orders  overspeeding  of  the  films.  A  film  might  be  run 
at  the  rate  of  70  feet  (70  turns  of  the  projector  crank)  per 
minute  without  undue  strain  to  the  film,  but  if  long  con- 
tinued it  will  inevitably  injure  the  projection  mechanism.  If 
one  will  but  pause  and  consider:  There  are  sixteen  pictures 
to  each  foot  of  film.  Each  picture  must  stop  dead  still  over 
the  aperture,  and  then  be  displaced  by  the  next  one  after 
exposure,  all  in  one-sixteenth  of  a  second  when  running  at 
normal  speed.  This  means  that  the  strip  of  film  between 
the  upper  and  lower  loops  must  start  and  stop  sixteen  times 
each  second.  If  the  crank  speed  be  increased  to  70  per 
minute  it  means  that  this  stoppage  and  starting  must  take 
place  at  the  rate  of  nineteen  per  second,  instead  of  sixteen. 

At  80  turns  of  the  crank  per  minute  it  means  that  twenty- 
two  pictures  (almost)  will  be  exposed  each  second.  Not 
only  must  the  strip  of  film  between  the  two  loops  be  started, 
against  the  considerable  pressure  of  the  tension  springs,  at 
this  terrific  speed,  but  also  the  intermittent  shaft,  star  and 
sprocket  must  also  be  started  and  stopped  at  the  same  rate. 
It  requires  but  slight  knowledge  of  mechanics  to  understand 
the  strain  thus  placed  on  the  sprocket  holes  of  the  light, 
fragile  film,  as  well  as  on  the  intermittent  movement  of  the 
projector.  Overspeeding  also  makes  necessary  a  tighter 
tension,  which  still  further  aggravates  the  damage.  The 
camera  which  took  the  scene  is  supposed  to  run  at  60  a 
minute.  Films  and  projection  machines  are  intended  to 
withstand  the  strain  of  60  a  minute  and  will  do  so.  When, 
however,  this  speed  is  exceeded  to  any  considerable  degree 
the  strain  multiplies  rapidly,  and  the  consequent  wear  and 
tear  is  several  times  what  it  is  at  normal. 

Effect  of  Loss  of  Definition. — One  factor  enters  very 
largely  into  projection  which  is  very  little  understood  by 
the  average  manager  and  operator.  This  matter  has  been 
called  to  my  attention  by  Mr.  Nicholas  Power  of  the 


FOR   MANAGERS    AND    OPERATORS 


153 


Nicholas  Power  Company,  and  while  I  have  never  thought 
of  it  in  that  connection  before  I  believe  Mr.  Power  is  ab- 
solutely correct. 

Patrons  frequently  complain  that  "pictures  hurt  their  eyes," 
even  when  there  is  no  trace  of  flicker.  Managers  and  oper- 
ators have  been  puzzled 
to  account  for  this.  Mr. 
Power's  explanation  of 
the  matter  is  as  follows : 
Take  a  carbon  copy  of 
a  letter  or  long  article, 
and  attempt  to  read  it. 
You  will  find  that  before 
you  have  read  very  far 
your  eyes  begin  to  hurt 
and  even  to  water.  The 
reason  for  this  is  found 

in  the  blurry  appearance  \  Figure  64. 

of  the  copy,  and  the 
more  blurry  the  carbon  the  greater  will  be  the  strain  on  the  eye. 
The  same  holds  true  with  pictures.  If  the  definition  on 
the  screen  be  not  absolutely  sharp,  the  effect  on  the  eye  is 
a  strain,  and  not  only  is  this  effect  present  where  there  is 

lack  of  definition 
through  fault  of  the 
camera  or  the  pro- 
jection lens,  but  it  is 
also  present  where 
there  is  a  travel  ghost. 
This,  it  seems  to 
me,  is  an  important 
point,  and,  moreover, 
it  is  a  new  point.  I 
believe  this  is  the 
first  time  it  has  re- 
ceived consideration. 
I  would  advise  man- 
agers to  look  into 
this  matter  and  to 

use  every  endeavor  to  have  the  definition  on  their  screen  as 
sharp  as  it  can  possibly  be  made  and  travel  ghost  entirely 
eliminated.  Of  course,  we  all  know  that  from  any  point  of 
view  the  loss  of  definition  and  travel  ghost  is  bad,  but  viewed 
in  this  light  it  becomes  doubly  obnoxious. 


Figure  65. 


154  MOTION    PICTURE   HANDBOOK 

Side  View. — Many  times  the  question  has  been  asked: 
"Why  do  the  screen  figures  .look  abnormally  tall  and  thin 
when  viewed  from  a  heavy  angle?"  This  is  clearly  ex- 
plained in  Fig.  64;  in  which  two  people,  C  and  D,  view  a 
figure  having  a  normal  width  of  A-B  on  screen  X  =  X.  C 
gets  the  full  benefit  of  this  width,  as  per  lines  A-B,  but  D 
only  gets  the  effect  of  width  as  per  dotted  line  B-E,  for 
reasons  which  are  self-evident. 

Keystone  Effect. — Where  the  machine  is  set  above  the  level 
of  the  screen  the  bottom  of  the  picture  will  be  wider  than  its  top, 
thus  producing  what  is  known  as  "keystone  effect,"  as  shown 
at  H,  Fig.  65.  This  effect  is  due  to  the  fact  that  the  light 
ray  spreads  out  as  it  travels,  and  to  the  further  fact  that  it 
must  travel  farther  to  reach  the  bottom  of  the  screen  than  it 
must  travel  to  reach  the  top  when  the  angle  of  projection  is 
downward. 

This  is  illustrated  in  Fig.  65,  in  which  A  is  the  lens  of 
the  projector,  B-S  the  screen  and  F-S  the  horizontal  distance 
of  projection,  H,  being  a  detail  to  show  shape  of  picture 
under  these  conditions.  If  the  top  of  light  rays  A,  B,  S,  are 
all  to  travel  the  same  distance  to  reach  the  screen,  then  the 
screen  would  necessarily  be  located  at  B-D,  and  the  picture 
would  have  its  normal  shape,  but  since  the  bottom  of  the 
screen  is  at  S,  it  follows  that  to  reach  the  top  of  the  screen 
the  light  rays  must  only  travel  from  A  to  B,  whereas  in 
order  to  reach  the  bottom  it  must  travel  from  A  to  S,  or  the 
distance  D-S  in  excess  of  distance  A-B.  Now  assuming  A-B 
to  be  60  feet  and  the  top  of  the  picture  to  be  15  feet  wide,  and 
the  distance  D-S  to  be  3  feet,  we  would  have  a  light  ray  which 
spreads  15  -^  60  =  .25  of  a  foot,  or  12-f-4  =  3  inches  with 
each  foot  of  throw.  Hence  it  follows  that  distance  D-S 
being  3  feet,  the  width  of  the  bottom  of  the  picture  would 
be  3X3  =  9  inches  greater  than  the  width  of  the  top  of  the 
picture.  The  same  thing  as  applied  to  a  40,  30  and  15  degree 
angle  on  an  80-foot  throw  is  fully  illustrated  in  Fig.  66. 

The  same  condition  prevails  when  the  machine  is  set  to  one 
side  of  the  center  of  the  screen,  except  that  in  this  instance 
the  keystone  effect  will  be  sidewise — that  is  to  say,  one  side 
of  the  picture  will  be  higher  than  the  other  side.  There  is, 
however,  this  difference:  The  up  and  down  keystone  effect 
is,  for  some  reason  which  I  have  never  been  able  to  under- 
stand, never  accompanied  by  as  great  a  tendency  to  out-of- 
focus  effect  as  is  the  side  keystone.  The  instant  the  machine 
is  set  to  any  considerable  distance  to  one  side  of  the  center 
of  the  screen  difficulty  is  encountered  in  getting  a  picture 


FOR   MANAGERS   AND   OPERATORS 


155 


Figure  66. 


156  MOTION    PICTURE    HANDBOOK 

which  is  sharp  all  over,  and  if  the  machine  be  set  much  to 
one  side  it  will  be  found  practically  impossible  to  get  even  a 
reasonably  good  picture.  It  is  no  unusual  thing,  however,  to 
have  a  machine  giving  a  fairly  sharp  definition  all  over  the 
picture  with  a  drop  in  projection  of  fully  40  feet  in  100.  Of 
course  a  portion  of  this  difference  in  effect  is  accounted  for  by 
the  fact  that  the  picture  is  wider  than  it  is  high,  but  this  does 
not  seem  to  explain  the  whole  thing,  as  a  fairly  sharp  picture 
may  be  had  with  very  steep  downward  pitch. 

The  keystone  effect,  so  far  as  the  outline  of  the  picture  is 
concerned,  may  be  corrected  by  filling  in  the  projector 
aperture  with  hard  solder,  and  then  carefully  filing  it  out 
until  the  picture  assumes  its  normal  shape  on  the  screen. 

The  best  and  in  fact  the  only  practical  way  to  do  this  is  to 
fill  in  with  solder  and  file  the  aperture  to  shape  when  the 
light  is  on,  first,  however,  having  removed  one  of  the  con- 
densing lenses  so  that  the  spot  will  be  very  large,  since  other- 
wise it  will  be  too  hot  to  work  in.  By  this  method  you  can 
watch  the  exact  effect  of  every  stroke  of  the  file  upon  the 
outline  at  the  screen.  Be  very  careful  that  you  do  not  get 
a  little  too  much  off,  because  if  you  do  you  will  have  to  do 
the  whole  job  over  again.  If  the  machine  sets  above  the 
screen  the  filing  will  have  to  be  done  on  the  sides  of  the 
aperture,  the  lower  part  of  the  aperture  being  made  widest. 
If  the  machine  sets  to  one  side  of  the  screen  then  the  top 
and  bottom  will  have  to  be  filled  in.  Before  beginning,  hang  a 
narrow  strip  of  black  tape,  weighted  at  its  lower  end,  with  its 
upper  end  just  where  the  lower  end  of  the  upper  corner  bend 
comes.  This  will  supply  guides  so  that  you  will  get  the  side 
lines  perfectly  straight  and  perpendicular.  Bevel  the  sides  of 
the  aperture  opening  slightly  on  the  screen  side. 

As  before  stated  the  outline  of  the  picture  can  be  corrected 
in  this  way,  but  the  distortion  of  the  picture  will  remain. 
That  cannot  possibly  be  corrected,  except  by  setting  the 
machine  lens  central  up,  down  and  sidewise,  with  the  center 
of  the  screen. 

The  out-of-focus  effect  which  accompanies  keystone  effect 
where  the  machine  is  set  to  one  side  of  the  center  of  the 
screen  may,  if  it  be  not  too  great,  be  corrected  by  loosening 
the  aperture  plate  and  placing  a  thin  strip  of  metal  under 
one  side,  the  idea  being  to  slightly  raise  one  side  of  the 
aperture  plate,  provided  it  be  a  type  of  machine  which  will 
allow  of  its  gate  being  squared  with  the  aperture  in  its  new 
position.  Up  and  down  keystone  effect  can  also  be  corrected  by 
blocking  the  upper  end  of  the  aperture  plate  out  somewhat ;  but 


FOR   MANAGERS    AND    OPERATORS  157 

this  cannot  be  carried  very  far,  or  trouble  with  the  tension  shoes 
will  be  encountered. 

Amperage 

(Also  see  Limit  of  Amperage,  Page  292.) 

The  number  of  amperes  to  be  used  for  the  projection  of  a 
given  size  picture  depends,  to  a  large  extent,  on  the  screen 
surface  used  and  the  kind  and  amount  of  auditorium  light- 
ing;'the  percentage  of  light  cut  by  modern  projectors  vary- 
ing but  little  from  50  per  cent. 

There  are  still  those  who  commit  the  error  of  assuming 
that  the 'distance  of  projection  (throw)  has  much  to  do  with 
the  necessary  volume  of  light;  also  there  are  still  those  who 
attempt  to  apply  the  well  known  law  that  "light  intensity 
diminishes  with  the  square  of  the  distance." 

Let  me  again  correct  these  impressions.  Provided  the 
lens  system  of  the  projector  be  properly  matched,  it  makes, 
within  reasonable  limits,  but  very  little  if  any  practical 
difference  what  the  distance  of  projection  is.  With  the 
arc  at  a  given  distance  from  the  condenser  a  certain  amount 
of  light  is  distributed  over  the  area  of  the  spot,  and  a  cer- 
tain percentage  of  this  light  intensity  passes  through  the 
aperture  of  the  projector  and,  of  course,  the  film.  If  the  lens 
system  is  properly  matched,  practically)  all  light  passing 
through  the  film  will  enter  the  objective  lens;  also  practically 
all  light  entering  the  lens  will  leave  it  (I  am  laying  aside, 
for  the  time  being,  the  absorption  of  light  in  passing  through 
glass);  and,  once  having  left  the  lens,  a  moment's  thought  will 
convince  even  the  most  skeptical  that  if  a  ray  of  light  can 
travel  ninety-three  millions  of  miles  from  the  sun  to  the 
earth,  a  difference  in  distance  as  between  50  and  100,  150  or 
even  250  feet  is  not  going  to  make  any  practical  difference, 
provided  the  atmosphere  be  even  reasonably  free  from  dust 
and  smoke,  which  would  cause  more  or  less  diffusion. 

In  Fig.  67  we  see  an  illustration  of  the  law :  "Light  in- 
tensity decreases  inversely  with  the  square  of  the  distance." 
In  this  illustration  A,  B  and  C  represent  different  positions 
of  a  screen.  Light  rays  emanating  from  a  central  source 
travel  in  straight  lines  in  all  directions.  It  requires  but  a 
glance  to  see  that,  this  being  the  fact,  these  light  rays  will 
spread  fanwise  as  they  travel,  and  that  in  position  C  the  screen 
would  receive  only  a  comparatively  small  percentage  of  the 
light  it  would  receive  if  it  were  in  position  A.  In  fact, 
screen  B  would  have  to  be  as  large  as  is  indicated  by  the 


158  MOTION    PICTURE    HANDBOOK 

dotted  lines  in  order  to  receive  the  same  total  illumination 
received  by  screen  A,  which  would,  of  course,  greatly  re- 
duce the  brilliancy  per  unit  of  area,  and  screen  C  would  need 
to  be  still  larger  in  order  to  catch  the  same  number  of  rays 
screen  A  receives.  This  is  a  very  plain  illustration  of  the 


Figure  67. 

law   in    question,   but   this    law    does    NOT  apply    to    projection, 
except  in  a  very  modified  fashion. 

In  a  projection  machine  we  have  an  arc  lamp  with  the 
crater  forced  into  a  position  where  it  will  face  the  con- 
densing lens  as  squarely  as  possible.  By  reason  of  this 
condition  a  certain  given  and  very  high  percentage  of  the 


FOR   MANAGERS    AND   OPERATORS  159 

light  emanating  from  the  crater  on  the  carbon  strikes  the 
rear  surface  of  the  condensing  lens,  and  is  by  that  lens 
projected  to  the  spot,  where  again  a  certain  definite  per- 
centage passes  through  the  aperture  of  the  machine.  Now 
the  light  which  passes  through  the  aperture  and  film  passes 
on  and  into  the  objective  lens,  where  it  is  given  a  certain 
definite  direction.  The  rays  do  not  spread  out  in  every  direc- 
tion, as  per  Fig.  67,  but  only  on  the  lines  determined  by  the 
curvature  of  the  lens,  therefore  the  light  intensity  of  the  screen 
is  proportional  to  the  total  candle  power  of  the  light  ray  at  the 
front  end  of  the  objective  lens  as  compared  to  the  area  of  the 
screen. 

Loss   of   Light  in   Lenses.— At   this   point   it  is,   I   think, 

proper  briefly  to  consider  the  loss  of  light  in  the  lens  system. 
It  is  a  well  known  and  established  fact  that,  in  passing 
through  glass,  light  loses  .a  certain  proportion  of  its  intensity. 
This  loss  has  been  variously  estimated  by  different  authors, 
but  it  appears  to  me  the  conclusion  arrived  at  by  Mr.  J. 
Frank  Martin,  of  Pittsburgh,  Pa.,  in  a  paper  entitled,  "The 
Illumination  of  Motion  Picture  Projectors,"  read  before  the 
Pittsburgh  section  of  the  Illuminating  Engineering  Society, 
April  18,  1913,  is  the  first  and  only  authoritative  statement 
concerning  the  loss  of  light  in  the  lens  system  of  a  projection 
machine. 

I  would  not  by  any  manner  of  means  wish  to  be  under- 
stood as  indorsing  the  conclusion  arrived  at  by  Friend 
Martin.  In  fact,  it  seems  to  me  those  conclusions  lead  to  an 
impossible  screen  effect,  but,  nevertheless,  as  I  before  said, 
they  are  the  only  authoritative  statements  I  have  ever  seen 
on  the  subject.  Mr.  Martin  says,  in  part: 

"Many  different  combinations  of  lenses  have  been  experi- 
mentally developed,  but  no  radical  changes  have  been  made 
from  the  earliest  form  used  in  the  magic  lantern.  The  lens 
system  and  the  losses  therein  are  illustrated  in  Fig.  68. 
The  projector  lens  system  has  been  built  up  with  a  point 
source  of  light  as  a  basis;  hence  the  low  efficiency  of  10  per 
cent,  is  not  surprising,  and  there  is  apparently  great  oppor- 
tunity for  improvement." 

The  diagram  will  be  of  great  interest  to  operators;  also 
it  will  have  for  him  some  surprises.  However,  I  do  not 
think  the  right  impression  is  conveyed  when  Mr.  Martin 
says  there  is  an  efficiency  of  10  per  cent,  at  the  screen.  This 
does  not  seem  to  me  to  be  a  fair  statement  of  fact.  As  I 
understand  it,  Mr.  Martin  assumes  an  efficiency  of  10,000  c.p.  at 


160 


MOTION    PICTURE    HANDBOOK 


the  arc,  meaning  by  this  that  the  surface  of  the  crater  itself  has 
a  total  light  efficiency  equal  to  10,000  c.p.,  but  after  the  rays 
have  spread  and  a  portion  of  them  have  been  lost  in  the 
interior  walls  of  the  lamphouse,  there  remains  only  an 
efficiency  of  200  c.p.  at  the  surface  of  the  front  condenser. 


i*v  ne#cf#r  70 


~<50' 


Figure  68. 


Now  what  I  understand  this  to  mean  is,  in  effect,  that  if  the 
area  of  the  crater  could  be  magnified  to  the  size  of  the  con- 
denser and,  without  considering  the  light  loss  in  the  interior 
lamphouse  walls,  it  still,  as  a  whole,  gave  off  10,000  c.p.,  the 
light  giving  power  per  unit  of  area  would  be  reduced  to  200 
c.p.,  or,  putting  it  in  another  way,  the  diminution  of  light 
intensity  per  unit  area  of  measurement  amounts,  by  reason 
of  the  spreading  of  the  light  rays,  to  a  difference  between 
10,000  and  200. 

And  now  comes  something  that  will  be  mighty  interesting 
to  the  average  operator,  viz.,  the  loss  of  70  per  cent,  in  the 
condenser  itself.  This  loss  Mr.  Martin  holds  is,  to  a  con- 
siderable extent,  due  to  the  use  of  low  grade  glass  in  cheap 
condensing  lenses.  The  lenses  used  in  the  test  were  a  pair 
of  6l/2  and  7l/2  plano-convex,  of  the  ordinary  variety.  The 
test  was  made  with  a  Sharp-Miller  photometer,  by  placing 
a  standard  test  plate  at  the  point  where  it  was  desired  to 
measure  the  brilliancy.  This  test  plate  is  a  smooth,  white 
surface  which  reflects  a  definite  proportion  of  the  light  from 
its  surface.  By  placing  such  a  test  plate  flush  with  the  sur- 


FOR   MANAGERS    AND   OPERATORS  161 

face  of  the  condenser,  next  the  arc,  and  measuring  the  light 
reflected  therefrom,  it  was  found  that  200  c.p.  was  the 
brilliancy  of  each  square  inch  of  the  condenser  surface.  The 
arc  had  been  previously  adjusted  and  placed  in  a  position 
that  gave  a  clear,  round  spot  at  the.  aperture  of  the  machine. 
When  this  test  plate  was  moved  to  the  surface  of  the  outer 
condenser,  and  the  indication  taken  in  the  same  manner, 
60  c.p.  per  square  inch  was  the  light  intensity  recorded,  which 
indicates  the  astonishing  loss  of  70  per  cent,  in  the  con- 
denser itself.  This  does  not,  at  first  blush,  appear  to  be 
reasonable,  nor  do  I  believe  it  represents  exactly  the  fact, 
because  a  slight  alteration  in  the  length  of  the  arc  may  (I 
don't  say  it  would,  but  it  might)  affect  a  considerable  differr 
ence  in  the  quality  of  the  light,  which  might  operate  to 
diminish  its  brilliancy.  Nevertheless,  whether  the  figures 
are  accurate  or  not  they  certainly  do  show  that  the  con- 
denser absorbs  an  enormous  percentage  of  the  light.  Nor 
are  we  altogether  surprised  that  this  is  the  fact  when  we 
remember  that  the  thin  filament  of  glass  contained  in  an 
incandescent  light  globe  causes  a  loss  of  3  per  cent.  You 
would  hardly  think  this  latter  were  possible,  but  illuminating 
engineers  tell  us  it  is  the  fact. 

This  tremendous  condenser  loss  certainly  points  to  the 
enormous  importance  of  using  high  class  condensing  lenses — 
the  best  that  can  be  had,  and  even  then  the  loss  would  be 
very  great.  The  inefficiency  of  the  condensing  lens  was  very 
thoroughly  proved  to  the  writer  when  he  witnessed  the 
demonstration  of  a  parabolic  reflector  designed  to  concen- 
trate the  light  without  the  use  of  condensing  lenses.  He  was 
literally  amazed  to  witness  the  projection  of  a  really 
brilliant,  beautiful  sixteen-foot  picture  with  only  slightly  in 
excess  of  12  amperes  of  current,  using  an  ordinary  muslin 
screen.  This  reflector,  or  light  concentrator,  has  never  as 
yet  been  got  into  a  form  where  it  is  practical  for  general 
motion  picture  work,  but  it  did  show  the  tremendous  gain 
which  would  be  made  possible  if  the  condenser  could  be 
eliminated.  Moreover,  the  light  had  a  white,  mellow,  pleasing 
quality  the  writer  has  never  seen  in  an  illumination  which  has 
passed  through  condensing  lenses. 

But  to  return  to  our  subject.  Referring  to  Fig.  68,  we 
find  that  the  test  plate,  when  placed  at  the  aperture  of  the 
machine,  showed  a  brilliancy  of  510  c.p.  per  square  inch,  but 
that  immediately  after  the  light  had  passed  through  the  film 
only  470  c.p.  was  shown,  which  indicates  a  loss  of  8  per  cent, 
in  the  film  itself.  The  film  used  was  a  clear  piece  from  which 


162  MOTION    PICTURE    HANDBOOK 

the  photographic  emulsion  had  been  removed.  Therefore 
it  appears  that  the  celluloid  of  the  film  itself  absorbs  8  per 
cent  of  the  light. 

And  now  comes  the  point  which  makes  this  whole  thing 
appear  to  me  as  rather  impossible,  except  viewed  from  the 
standpoint  of  proportiotls  of  loss.  It  seems  to  me  that,  if 
the  aperture  had  an  area  of  one  square  inch,  and  the  light 
brilliancy  passing  through  it  were  only  470  c.p.  per  square 
inch,  then  the  screen  itself  could  only  have  a  brilliancy  per 
square  inch  equal  to  470  divided  by  the  total  square  inch  area 
of  the  screen,  which  would  give  us  an  actual  screen  brilliancy 
of  only  a  very,  very  small  fraction  of  one  candle  power.  As 
a  matter  of  fact  even  that  result  would  be  too  high,  because  the 
area  of  the  aperture  is  only  about  three-quarters  of  one  square 
inch,  therefore  the  real  screen  brilliancy  would  be  three- 
quarters  of  470,  divided  by  the  square  inch  screen  area,  and 
even  that}  would  be  reduced  by  the  8  per  cent,  loss  in  the 
objective  lens. 

I  have  given  this  matter  space  because  of  the  fact  that  it 
points  an  entrance  to 'a  road  which  needs  thorough  explor- 
ing, and  needs  it  badly,  too.  The  projection  lens  itself, 
being  of  very  high  grade  glass,  only  entails  a  loss  of  5  to  12 
per  cent.,  averaging,  Mr.  Martin  says,  8  per  cent.  The  thin 
bulb  of  an  incandescent  lamp,  made  of  ordinary  glass,  causes 
a  light  loss  of  3  per  cent.  Now  the  total  glass  in  the  two 
combinations  of  the  ordinary  projection  lens  will,  I  think, 
measure  about  five-eighths  of  an  inch  in  thickness.  If  it  is  true 
that  less  than  one-thirty-second  of  an  inch  of  ordinary  glass 
causes  a  light  loss  of  3  per  cent.,  and  approximately  five- 
eighths  of  an  inch  of  very  high  grade  glass  causes  a  loss 
of  only  about  8  per  cent.,  it  would  seem  to  be  readily  apparent 
that  there  would  be  an  enormous  gain  in  using  very  high  grade 
optical  glass  for  condensing  lenses. 

It  is  but  a  step  from  this  result  to  the  inevitable  conclusion 
tbat  there  is  a  huge  duty  devolving  upon  machine  manu- 
facturers to  evolve  some  method  of  absolutely  stopping  the 
breaking  of  condenser  lenses,  to  the  end  that  really  high- 
class,  expensive  ones  may  be  used.  Already  the  Elbert  and 
Preddy  condenser  holders  have  paved  the  way.  Altogether 
too  little  attention  'has  been  paid  to  this  extremely  important 
matter  in  the  past. 

To  get  back  to  our  main  subject.  Broadly  speaking  the  num- 
ber of  amperes  necessary  to  produce  a  given  curtain  illumination 
will  depend  upon  the  number  of  square  feet  contained  in  the 
screen,  the  character  of  surface  of  the  screen  and  the  percentage 


FOR    MANAGERS    AND    OPERATORS  163 

of  light  cut  by  the  revolving  shutter.  As  set  forth,  the  modern 
projection  machine  will,  under  the  best  conditions,  cut  approxi- 
mately 50  per  cent,  of  the  light,  and  under  adverse  conditions 
may  cut  somewhat  more  than  this,  though  the  variation  either 
way  from  50  per  cent,  will  be  but  little.  The  area  of  the  screen, 
and  the  character  of  its  surface,  however,  are  largely  governing 
factors.  Suppose  we  are  projecting  a  picture  8  by  10  feet  at  60 
feet.  In  a  space  8  by  10  feet  are  80  square  feet  of  surface.  Now, 
understanding  that  practically  all  light  rays  leaving  the  objective 
lens  reach  the  screen,  while  light  rays  are  really  numberless,  let 
us  suppose,  for  purpose  of  illustration,  that  we  have  exactly  160 
rays  of  light  leaving  the  projection  lens.  This  would,  of  course, 
mean  that  each  square  foot  of  screen  would  be  illuminated  by 
just  two  rays  of  light. 

Now  suppose  we  change  our  lens  to  one  projecting  a  picture 
12  by  16  feet,  which  would  have  192  square  feet  of  surface.  The 
total  light  remains  the  same,  but  the  surface  has  been  more  than 
doubled.  It  therefore  follows  that  the  light,  being  spread  over 
more  than  twice  the  area,  has  been  weakened,  so  far  as  screen 
illumination  be  concerned,  by  more  than  one-half.  Where  we 
formerly  had  an  illumination  equal  to  that  produced  by  two  rays 
for  every  square  foot  of  screen  surface,  we  now  have  an  illu- 
mination less  than  that  equal  to  one  ray  to,  the  square  foot.  We 
still  have  exactly  the  same  total  amount  of  light,  but  have,  in 
limited  degree,  invoked  the  law  of  inverse  ratio  already  spoken  of. 

We  thus  see  that  illumination  decreases  as  the  area  over  which 
it  is  spread  is  increased.  It  therefore  follows  that  if  the  size  of 
the  picture  (area)  be  increased,  it  will  be  necessary,  in  order  to 
maintain  the  same  brilliancy,  that  the  power  of  the  light,  or,  in 
other  words  the  amperage,  be  also  increased  to  a  value  which  will 
supply  to  each  square  foot  of  screen  surface  the  same  intensity 
of  illumination  it  received  in  the  smaller  picture. 

In  the  second  edition  of  the  Handbook  I  gave  an  amperage 
table  which  was  presumed  to  be  satisfactory  for  use  with  any 
good,  non-reflective  screen,  such  as  a  plaster  wall,  calcimine 
surface,  white  muslin,  etc.  I  see  no  reason  for  making  any 
changes  in  this  table,  except  to  say  that  the  modern  tendency  is 
for  more  brilliant  illumination,  and  this  would  increase  the 
figures  given,  I  believe,  by  very  nearly  25  per  cent.  In  other 
words,  high-class  theatres  of  today  would  probably  use  nearer  50 
amperes  than  38  on  a  15  foot  picture.  I  shall,  however,  give  the 
tables  unchanged,  but  with  the  foregoing  modification.  Those 
who  wish  to  follow  up-to-date  practice  are  recommended  to 
increase  the  amperage  given  by  25  per  cent.  In  the  "Amperes 
A.  C."  column  of  the  table  I  have  made  60  amperes  the  limit — 


164      ,         MOTION    PICTURE   HANDBOOK 

this  by  reason  of  the  fact  that  operating  room  transformers 
(compensarcs,  inductors,  economizers,  etc.)  almost  without  ex- 
ception have  a  60  ampere  maximum  capacity.  As  a  matter  of 
fact,  however,  not  less  than  90  amperes  A.  C.  should  be  used  on 
a  20  foot  picture  and  an  18  foot  picture  should  have  not  less  than 
75  or  80.  Where  A.  C.  is  u^sed  on  large  pictures  I  would  recom- 
mend two  economizers  wired  in  multiple.  The  figures  given 
in  the  table  are  based  on  the  presumption  that  the  screen  surface 
is  in  good  condition. 

TABLE  3. 

Amperes  Amperes 

Picture.  Area  Sq.  Ft.  D.  C.  A.  C. 

6.75  x  9  61  20  35 

7.5  xlO  75  20  35 

8.25x11  91  20  35 

9      x!2  108  22  35 

9.75x13  127  25  38 

10.5   x!4  147  29  44 

11.25x15  169  33  50 

12   x!6  192  38  58 

12.75  x  17  216  43  60 

13.5  x!8  243  45  60 

14.25x19  268  45  60 

15   x20  300  45  60 

Another  governing  factor  in  j  the  matter  of  amperage  is  the 
type  of  screen  surface  used.  There  are  on  the  market  a 
number  of  semi-reflective  so-called  metallic  surf  ace  screens, 
and  one  make  of  glass  surface  screen.  The  principal  value  of 
these  screens  lies  in, the  fact  that  a  greater  curtain  brilliancy 
may  be  obtained  with  a  very  considerable  less  current  con- 
sumption than  is  necessary  with  the  non-reflective  screen 
surfaces.  This  matter  will,  however,  be  dealt  with  more 
extensively  under  the  heading  "The  Screen,"  Page  166. 

We  have  learned  that  screen  brilliancy  will  not  depend  up- 
on the  total  amount  of ,  light  projected  to  the  surface  of  the 
screen,  but  upon  the  total  amount  of  light  projected  to  each 
square  foot  of  screen  surface.  This  brings  us  to  the  inevitable 
conclusion  that 

A  certain  given  amperage  per  square  foot  of  screen  surface  will 
give  a  certain  definite  brilliancy  of  illumination  to  the  screen, 
other  things  being  equal. 

There  are,  of  course,  many  equations,  entering  in  less  degree 
into  this  matter.  We  are  only  speaking  in  generalities.  For 
instance,  curtain  brilliancy  will  to  a  certain  extent  depend 
upon  the  set  of  the  carbons  and  the  angle  of  the  lamp,  but 


FOR  MANAGERS  AND  OPERATORS 


165 


at  this  stage; of  affairs  even  the  tyro  operator  is  supposed  to 
have  a  fairly  good  knowledge  of  carbon  setting  and  lamp 
angle,  since  there  is  but  one  correct 'setting  and  one  correct 
angle,  modified  only  to  some  extent  by  the  pitch  of  the  pro- 
jection,  machine  itself. 

The  amperage  will  also  depend,  to  some  slight  extent,  on 
the  clearness  of  the  atmosphere,  to  a  considerable  extent 
and 'amount  on  the  auditorium  lighting,  upon  the  density  of 
the  film,  upon  the  grade  of  lenses  used,  and  the  matching  of 
the  optical  system.  All  these  are  more ,  or  less  potent  fac- 
tors, and  no  set  rule  can  be  given,  nor  can  any  table  be 
given  which  will  meet  all  conditions. 

The  following  very  interesting  table  shows  the  increased 
percentage  of  light  made  necessary, by  increasing  the  size 
of  the  picture,  for  instance:  If  you  have  a  six  foot  picture 
and  desire  to  .increase  it  to  seven  feet:  The  area  of  your 
six  foot  picture  is  26.4  and  the  area  of  your  seven  foot  pic- 
ture is  35.9  square, feet,  an  increased  area  of  9.5  square  feet, 
which  will  require  36  per  cent  more  light.  In  other  words, 
to  illuminate  a  seven  foot-,  picture  to  the  same  brilliancy  as 
a  six  foot  picture  would  require  36  per  cent  more  light.  The 
percentage,  however,  decreases  as  the  size  of  the  picture 
increases;  that  is  to  say,  there  is  a  less  percentage  between 
the  ten  and  thirteen  foot  than  between  the  eight  and  twelve 
foot  picture.  This  table  ought  to  form  a  very  interesting 
study  for  operators.  It  Js  based  on  the  fifteen-sixteenths 
inch  aperture. 

TABLE  4. 


Width 
in  feet. 

6 

7 

8 

9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 


Height 
in  feet. 

4.40 

5.13 

5.87 

6.60 

7.33 

8.07 

8.80 

9.53 

10.27 

11.00 

11.73 

12.47 

13.20 

13.93 

14.67 


Area 
sq.  feet. 

26.4 

35.9 

46.9 

59.4 

73.3 

88.7 

105.6 

123.9 

143.7 

165.0 

187.7 

212.0 

237.6 

264.7 

293.3 


Area  increase 
in  sq.  feet. 

*9.5 
11.0 
12.5 
13.9 
15.4 
16.9 
18.3 
19.8 
21.2 
22.7 
24.2 
25.6 
27.1 
28.6 


Percentage 

of  increase 

area. 

36 
31 
26 

23 
21 
19 
18 
16 
15 
14 
13 
12 
11 
11 


166  MOTION    PICTURE    HANDBOOK 

The  Screen 

THE    particular    and    only    function    performed    by    the 
screen  of  a  moving  picture  theatre  is  to  reflect  "picture 
light."     We  see  the  picture   precisely   for   the   same 
reason  that  we  see  any  other  object.    As  light  rays  are  re- 
flected from  various  objects  to  the  eye,  so,  in  projection,  light 
rays  reflect  from  the  screen  to  the  eye.    The  picture  appears 
plainer,  sharper  and  better  if  "picture  light"  alone  is  reflected 
and  if  the  "picture  light"  is  abundant. 

There  is  very  great  difference  in  screen  surfaces  and  in 
results  from  the  various  surfaces,  yet  IT  is  UTTERLY  IMPOSSIBLE 

TO  JUDGE  OF  THE  COMPARATIVE  VALUE  OF  RESULTS  OBTAINED  FROM 
VARIOUS  SCREEN  SURFACES  UNLESS  THEY  BE  PLACED  SIDE  BY  SIDE, 
SO  THAT  THE  SAME  PICTURE  MAY  BE  PROJECTED  BY  THE  SAME 
LIGHT,  ONE  HALF  OF  IT  ON  ONE  SCREEN  AND  THE  OTHER  HALF  ON 

THE  OTHER.  It  is  impossible  to  properly  judge  of  screen  surface 
values  by  looking  at  screens  in  different  theatres,  by  reason  of 
the  fact  that  there  are  seldom  or  never  two  screens  in  neighbor- 
ing houses  where  all  factors  are  equal  and  the  working  con- 
ditions are  precisely  alike.  The  brilliancy  of  the  projection 
light  may  be  different,  due  to  (a)  difference  in  amperage, 
(b)  in  carbon  set,  (c)  in  carbons,  (d)  quality  of  current, 
(e)  machine  shutter.  Also  general  results  may  be  altered 
by  difference  in  the  decoration  of  the  theater  auditorium;  in 
the  border  surrounding  the  screen;  in  the  length  and  width 
of  the  theatre;  in  the  distance  of  the  screen  from  the  audi- 
torium proper;  in  the  size  of  the  screen;  in  the  angle  of  the 
throw,  or  in  other  things.  In  fact  these  many  and  varying 
equations  make  it  absolutely  impossible  to  realize  the  true 
value  of  a  screen  surface  by  the  plan  of  going  from  one 
theatre  to  another,  depending  on  the  eye  alone  to  judge 
relative  values.  For  example,  changing  from  a  small  screen 
to  a  large  screen  will  cause  the  "picture  light"  to  appear,  by 
comparison,  less  brilliant,  assuming  other  conditions  to  be 
equal  in  both  cases.  A  change  from  a  screen  of  100  square 
feet  area  to  one  of  200  square  feet  area  will  cause  the  large 
screen,  if  the  two  surfaces  be  alike,  to  appear  50  per  cent, 
less  brilliant  than  the  smaller. 

It  is  even  impossible  accurately  to  judge  of  different  screen 
surfaces  by  projecting  a  picture  on  one  screen  and  then  sub- 
stituting the  other  therefor,  projecting  upon  it  the  same 
picture.  This  by  reason  of  the  fact  that  the  light  may  not 
be  the  same.  Something  may  have  happened  to  drop  the 
supply  voltage  slightly,  which  would  effect  the  amperage  at 


FOR   MANAGERS    AND   OPERATORS  167 

the  arc,  and  hence  the  light.  The  operator  may  not  have  his 
carbons  adjusted  precisely  the  same  in  both  instances,  which 
would  or  might  cause  a  change  in  the  screen  brilliancy.  In 
view  of  these  facts  the  only  right  way  is  the  one  I  have  sug- 
gested. That  kind  of  test  is  absolutely  fair  to  everybody 
and  it  is  not  a  difficult  one  to  make  either. 

I  would  most  emphatically  warn  the  operator  and  manager 
of  the  danger  of  judging  hastily  as  between  screen  sur- 
faces. I  would  also  caution  managers  and  operators  against 
the  too  ready  acceptance  of  the  statements  of  salesmen  as 
gospel  truth.  Salesmen  are  employed  to  sell  goods,  and  some  of 
them,  I  am  sorry  to  say,  don't  always  confine  themselves  to 
statements  which  the  facts  will  bear  out. 

As  a  matter  of  fact  I  now  have  an  instance  before  me  in 
which  an  exhibitor  paid  $75.50  for  a  screen.  It  was  a  good 
screen,  too,  the  surface  being  guaranteed  for  five  years.  But 
not  very  long  after  it  was  installed  along  came  a  nice,  smooth- 
talking  artist,  in  the  shape  of  a  salesman  for  another  brand  of 
screen.  Now  this  other  brand  of  screen  was  not  one  iota 
better,  even  if  it  was  really  as  good,  as  the  screen  the  man 
already  had,  yet,  as  absurd  as  it  seems,  the  salesman  actually 
talked  the  manager  into  paying  $225  for  a  new  screen.  The 
part  of  this  which  makes  the  transaction  particularly  dis- 
honest is  the  fact  that  the  new  screen  could  unquestionably 
have  been  sold  at  a  good  profit  for  the  same  price  he  paid 
for  his  other  one,  viz:  $75.50.  Verily  there  seems  to  be  a 
new  sucker  born  every  minute,  and  some  of  these  are  found 
in  moving  picture  theatre  managerial  capacities. 

The  time  will,  I  presume,  come  when  the  screen  business 
will  settle  down  to  a  solid  basis,  and  some  type  of  screen 
surface  will  be  found  to  be  best  and  become  standard.  At 
the  present  time,  however,  I  cannot  do  more  than  point  out 
to  theatre  managers  and  to  operators  the  necessity  for  demand- 
ing that  screen  salesmen  give  them  at  least  reasonable  proof 
of  the  correctness  of  their  statements,  and  that  proof  is  best 
given  by  actual  demonstration  as  before  outlined.  It  is  not  at 
all  impossible  for  a  screen  salesman  to  carry  with  him  a 
sample  surface  large  enough  to  cover  half  of  any  ordinary 
theatre  screen.  Make  him  hang  the  sample  up  over  half  of 
your  screen  and  show  you,  always  remembering  that  a  new, 
clean  screen  surface  is,  of  course,  somewhat  more  brilliant  than 
one  you  have  been  using  for  a  year  or  two.  Don't  attempt  to 
judge  from  a  small  sample,  however.  Make  him  cover  one-half 
of  your  screen  with  his  sample. 


168  MOTION    PICTURE   HANDBOOK 

As  a  matter  of  fact,  when  it  comes  right  down  to  absolute 
accuracy,  it  would  be  necessary  to  build  a  screen  to  meet  the 
requirements  of  each  individual  house,  but  this  is,  of  course, 
impractical,  nor  would  the  added  benefit  justify  the  necessary 
amount  of  labor  and  extra  expense  involved. 

Light.— As  stated,  the  only  function  of  the  screen  is  to  re- 
flect light.  Therefore,  in  order  to  understand  results  emanat- 
ing from  a  certain  screen  surface  we  must  first  understand  a 
few  of  the  many  laws  governing  light  action.  Light  travels 
at  the  almost  incomprehensible  speed  of  192,000  miles  a 
second.  This  speed  is  such  that  we  have  no  way  of  controlling 
it;  therefore  its  speed  cannot  be  altered.  This  is  an  item 
that  is  of  no  interest  to  the  operator,  except  as  a  matter  of 
general  information.  There  are  two  kinds  of  reflection,  viz: 

Regular  Reflection  and  Diffuse  Reflection.— Regular  reflec- 
tion occurs  when  light  strikes  a  smooth,  polished  surface  and 
is  not  broken  up  and  scattered,  as,  for  instance,  the  reflection 
from  a  looking  glass.  Example:  We  see  ourselves  in  a 
mirror  because  light  reflects  from  our  face  to  the  glass,  and 
comes  from  the  glass  into  our  eyes  without  being  scattered 
or  diffused. 

Diffuse  reflection  occurs  when  light  comes  to  the  eye  from 
a  body  which  has  a  roughened,  unpolished  surface,  which  by 
reason  of  its  roughness,  scatters  or  diffuses  the  light  rays. 

Reason  for  the  Haze. — Surfaces  which  have,  to  a  certain 
extent,  both  the  elements  of  polish  and  roughness,  reflect 
both  regular  and  diffuse  reflection,  and  thus  produces  a  haze, 
by  reason  of  the  fact  that  the  regular  reflection  is  superim- 
posed over  or  upon  the  diffused  reflection.  This  is  a  pecul- 
iarity of  the  polished  metallic  screen  surface,  and  explains  the 
reason  for  the  failure  of  many  home-made  metallic  surface 
screens. 

Light  Travels  in  Straight  Lines.— Light  rays  travel  from 
their  source  to  a  surface  in  perfectly  straight  lines,  and  when 
the  light  is  reflected  from  a  surface  to  the  eye  it  again 
travels  in  perfectly  straight  lines,  providing,  of  course,  the 
air  or  space  between  be  a  perfectly  transparent  medium,  of 
uniform  density.  Light  may  travel  from  one  surface  to  an- 
other several  times,  and  the  direction  of  its  rays  change  in 
each  instance,  but  the  traveling  is,  nevertheless,  always,  subject 
to  change  of  density  in  the  medium,  in  straight  lines. 

When  light  strikes  a  roughened  surface,  the  minute  rough- 
ened elements,  which  we  may  term  "peaks  and  depressions," 


FOR    MANAGERS    AND    OPERATORS  169 

will  cause  it  to  scatter  and  reflect  in  all  directions.  The  direc- 
tion of  the  reflected  rays  depend  upon  the  angle  of  these  minute 
peaks  or  depressions,  and  upon  their  location  with  reference 
to  the  source  of  light.  "Picture  light"  projected  upon  a 
screen  is  reflected  from  the  screen  into  the  eye  from  the  vari- 
ous peaks  and  depressions  upon  the  screen  surface,  and  is 
scattered  in  a  narrow  or  wide  angle  in  exact  proportion  to 
their  size. 

Peaks  and  Depressions. — These  peaks  and  depressions  are 
small,  and,  as  a  general  proposition,  invisible  to  the  naked 
eye.  A  single  ray  of  light  is  of  exceedingly  small  dimensions. 
Scientists  tell  us  that  a  bundle  composed  of  thirty-six  light 
rays  has  the  same  area  as  that  of  an  ordinary  human  hair. 
The  peaks  and  depressions  which  scatter  light  may  be  just  as 
minute  as  is  the  diameter  of  a  light  ray.  It  is  not  to  be 
understood  that  I  am  referring  to  a  surface  so  rough  that 
the  human  eye  can  see  the  roughness.  A  surface  may  have 
a  rough  matte  appearance,  and  yet  the  minute  elements  in 
that  surface  may  be  very  smooth,  and  therefore  not  cause 
perfect  diffusion  of  the  light,  whereas  a  surface  which  may 
appear  smooth  to  the  eye  might  be  of  such  character  that  it 
would  scatter  light  rays  in  all  directions,  and  thus  create  per- 
fect diffusion.  In  other  words  light  .rays  and  elements  of 
surface  that  scatter  light  are  both  almost  of  an  infinitely 
small  dimension. 

Matte  Surfaces. — It  must  be  understood  that,  given  the 
peaks  and  depressions,  as  above  set  forth,  there  is  an  added 
value  and  a  very  decided  added  value  if  the  surface  of  the 
screen  be  also  visibly  roughened,  that  is  to  say,  if  it  be  of  a 
matte  character.  This  matte  or  visible  roughness  is  not  an 
absolute  necessity,  provided  the  smooth  surface  be  of  the 
proper  character,  but  it  is  nevertheless  eminently  desirable 
since  it  adds  very  materially  in  the  production  of  a  perfect 
picture.  True,  the  matte  surface  has  little  or  nothing  to  do 
with  the  actual  diffusion  of  light,  but  nevertheless  it  per- 
forms another  important  function,  in  that  it  enables  the  eye 
to  see  the  picture  more  clearly  and  in  greater  detail  when 
viewed  from  a  side  angle. 

Interfering  Light. — One  of  the  prolific  causes  of  failure  to 
secure  clearness,  brilliancy  and  beauty  in  the  picture  is  what 
may  be  termed  "interfering  light."  Interfering  light  is  any 
light  other  than  "picture  light"  which  strikes  the  surface  of 
the  screen.  It  may  be  caused  by  (a)  stray  light  beams  from 
the  operating  room,  which  strike  the  wall  or  ceiling  and  are 


170  MOTION    PICTURE    HANDBOOK 

reflected  to  the  screen.  These  rays  usually  emanate  from  the 
condenser;  they  can  be  and  by  all  means  should  be  elimi- 
nated, (b)  Daylight,  which  is  a  most  prolific  cause  of  poor 
results  at  matinee  performances.  It  is  amazing  how  little  at- 
tention managers  and  operators  pay  to  the  thorough  excluding 
of  daylight  from  the  auditorium  at  matinee  performances.  Any 
daylight  which  reaches  the  screen,  no  matter  how  slight 
in  amount,  is  distinctly  detrimental  to  the  picture.  That 
is  an  absolute  fact,  which  it  seems  to  me  any  operator 
or  manager  ought  to  realize  and  understand,  (c)  House 
lights  improperly  arranged,  or  improperly  shaded.  This  is 
another  point  concerning  which  some  managers  display  an 
astonishing  amount  of  crass  ignorance  or  carelessness  or 
both.  I  have  actually  gone  into  a  theatre  of  considerable 
pretension,  charging  a  good  admission  price,  and  found 
the  white  light  from  incandescent  lamps  shining  directly  on 
the  screen,  or  found  the  white  light  shaded  from  the  screen 
but  glaring  directly  into  the  eyes  of  the  audience.  I  do  not 
care  to  take  up  the  matter  of  house  lighting  here,  but  under 
the  proper  heading  these  things  will  be  dealt  with  and  such 
information  as  is  available  will  be  given  on  the  subject  of 
house  lighting. 

Exhibitors  and  operators  should  be  continually  examining  the 
screen,  keeping  a  sharp  lookout  for  stray  light.  They  can  only 
do  this  best  when  the  projecting  machine  is  not  working — no 
picture  or  projection  light  on  the  screen.  The  screen  should 
then  look  the  same  all  over,  with  absolutely  no  shadows. 

After  having  examined  the  screen,  with  the  entrance  doors 
closed,  open  them  and  see  whether  there  is  any  difference, 
and  whether,  when  the  entrance  and  exit  doors  are  swung 
open,  shadows  appear  on  the  screen.  If  so,  then  the  neces- 
sary steps  should  be  taken  to  exclude  the  rays  which  cause 
these  shadows.  A  few  screens  or  double  doors  will  very 
likely  remedy  the  matter,  remembering  always  that  at  matinee 
performances  the  shades  on  the  windows  must  be  absolutely 
light  tight  in  order  to  get  the  best  effect.  This  is  best  accom- 
plished by  tight  fitting  wood  or  metal  shutters,  though  two 
dark-colored  shades,  with  their  edges  running  in  grooves  not 
less  than  one  inch  deep,  will  serve.  One  will  do  fairly  well, 
but  is  likely  to  develop  pinholes;  two  are  much  better. 

Standing  beside  the  screen,  looking  toward  the  auditorium, 
there  should  be  no  light  visible  to  the  eye  at  any  point.  If 
there  is,  then  that  light  is  reaching  the  screen  and  doing  injury 
to  the  projection. 


FOR    MANAGERS    AND    OPERATORS  171 

Indirect  lighting  has  been  one  of  the  best  aids  in  elimina- 
ting stray  light  from  incandescent  lamps,  but  it  is  often  improp- 
erly installed,  and  in  many  instances  an  indirect  lighting  fixture 
reflecting  light  against  the  ceiling  and  thence  to  the  screen  will 
cause  more  interfering  light  than  any  other  possible  installation. 
This  by  reason  of  the  general  practice  of  allowing  too  many 
and  wrongly  located  fixtures  to  be  illuminated  during  the  show, 
and  too  much  illumination  per  fixture.  See  "Lighting  Audi- 
torium." 

Tolerably  dark  wall  decorations  are  a  great  aid  in  elimina- 
ting stray  light;  also  they  are  more  restful  to  the  eye.  Dark 
colors,  such  as  green,  give  the  picture  greater  contrast,  and 
absorb  interfering  light.  Daylight,  however,  is  not  only  the  most 
difficult  of  all  stray  light  to  exclude,  but  is  also  the  hardest  to 
absorb,  and  in  hundreds  of  instances  its  presence  robs  the  picture 
of  beauty  and  detail.  Dark  decorations  on  the  walls,  however, 
can  easily  be  carried  to  excess.  There  is  room  for  good 
judgment  and  common  sense  here.  It  won't  do  to  make  the 
theatre  gloomy;  there  is  an  extreme  both  ways. 

Distribution  of  Light. — The  screen  not  only  reflects  light 
to  the  eye  located  at  one  point,  but  the  degree  of  roughness 
in  its  surface  causes  the  distribution  of  light  in  all  directions 
toward  and  throughout  the  auditorium  of  the  theatre,  so  that 
the  picture  becomes  visible  from  every  point  therein,  and 
if  the  screen  surface  be  such  that  distribution  is  even,  then 
the  picture  will  be  as  bright  from  one  point  as  it  will  from 
another. 

In  fact  one  of  the  important  points  of  difference  which  ap- 
pears when  comparing  various  screen  surfaces  is  the  difference 
in  the  direction  these  surfaces  reflect  the  picture  light. 

We  may  properly  divide  screen  surfaces  into  four  classes, 
viz:  three  classes  of  direct  projection  screens  and  one  class 
of  rear  projection  screens. 

First:  A  White  Wall  or  Sheet. — These  surfaces  were  in 
general  use  for  many  years,  and  are  still  used  to  a  large  ex- 
tent, particularly  in  the  smaller  towns.  The  white  sheet 
should  be  made  of  a  reasonably  good  grade  of  bleached  mus- 
lin, which  may  be  had  as  wide  as  108  inches.  It  must  be 
stretched  perfectly  tight  and  be  entirely  free  from  sags  and 
wrinkles.  The  plaster  wall  needs  no  description.  It  must, 
of  course,  be  perfectly  flat  and  finished  with  a  white,  hard 
coat. 

When  light  strikes  the  white  wall  or  sheet  the  peaks  and 
depressions  are  so  large,  as  compared  with  the  wave  length 
of  light,  that  the  light  is  reflected  in  very  wide  angles,  and  on 


172  MOTION    PICTURE   HANDBOOK 

this  account  a  great  proportion  of  the  light  is  lost  to  the 
auditorium  proper.  The  proof  of  this  is  that  a  white  wall 
will  appear  brighter  when  one  is  up  close  to  it  or  to  the  side 
of  it  than  will  any  other  screen,  whereas  it  will  appear  darker 
in  front  and  from  the  various  points  in  the  auditorium  of  the 
theatre.  A  metallized  screen,  or  mirror  screen  placed  against 
such  a  surface,  will  show  a  very  great  difference  in  brilliance 
of  illumination.  Therefore  it  is  not  possible  to  secure  any 
very  high  percentage  of  efficiency  with  a  white  wall  or 
cloth  screen,  as  compared  with  the  efficiency  secured  with 
semi-reflecting  screen  surfaces,  because  much  of  the  light 
from  the  wall  or  sheet  is  not  reflected  to  the  viewing  space 
of  the  auditorium,  but  in  other  directions. 

Second:  Metallized  Screens. — Screen  surfaces  coated  with 
various  secret  compounds  containing  more  or  less  aluminum 
or  other  metallic  substances  are  now  quite  popular.  Metallic 
screens  have  for  their  base  some  kind  of  cloth,  to  which  is 
applied  a  preparation  containing  a  percentage  of  aluminum 
or  bronze,  though  as  a  matter  of  fact  in  some  of  the  modern 
"metal"  surfaces  but  little  actual  metal  is  used.  Screeni 
also  have  been  made  from  tinfoil,  attached  to  cloth  and 
coated  with  celluloid.  This  formed  the  surface  of  the  "Day 
arid  Night"  screen  which  was  exploited  for  a  considerable  time. 

Bronzes  and  aluminum  paints  are  difficult  and  impractical  to 
apply  in  such  manner  as  to  secure  perfect  light  diffusion,  and 
the  exhibitor  should  always  buy  such  screens  from  reliable 
manufacturers  who  make  a  study  of  the  preparation  of  such 
surfaces,  and  who  usually  supply  stretching  devices  which  allow 
of  the  screen  being  properly  installed. 

Results  from  metallized  surface  screens  depend  upon  the 
character  of  the  surface.  Evidence  that  the  peaks  and  de- 
pressions on  many  metallic  surface  screens  are  smaller  than 
on  a  white  wall  or  sheet  may  be  had  by  viewing  the  surface 
with  a  microscope,  and  when  this  is  the  fact,  the  effect  is 
visible  to  the  eye  by  viewing  the  screen  from  an  angle  and 
noticing  the  difference  in  the  amount  of  light  reflected  from 
the  side  and  the  amount  reflected  straight  back.  You  will 
usually  find  that  away  up  to  one  side  the  "picture  light"  be- 
comes weaker,  but  as  you  go  in  front  of  the  screen,  at  some 
distance  away,  it  becomes  very  bright. 

For  a  wide  house  a  special  surface  should  be  made  which 
will  distribute  light  at  rather  a  wide  angle,  while  for  a  nar- 
row house  the  highest  efficiency  is  produced  by  a  brilliant 
surface  which  concentrates  the  light  to  a  narrow  viewing 
angle. 


FOR    MANAGERS    AND   OPERATORS  173 

The  reflection  of  light  by  the  screen  is  just  as  difficult  and 
important  an  optical  problem  as  is  the  projection  of  the  pic- 
ture itself,  and  even  as  a  lens  which  projects,  a  9  by  12  picture 
at  a  certain  distance  does  not  and  cannot  project  a  16  foot 
picture  at  the  same  distance,  a  screen  which  reflects  evenly  at 
a  narrow  angle  cannot  at  the  same  time  reflect  evenly  at  a  wide 
angle. 

Third:  Mirror  Screens. — This  surface  consists  of  a  sheet  of 
plateglass,  the  back  of  which  is  coated  precisely  the  same  as 
is  an  ordinary  plateglass  mirror.  After  the  back  has  been 
silvered,  its  face  is  ground  to  a  dull  finish,  which  is  made 
rough  or  smooth,  according  to  the  conditions  under  which  it 
is  to  work.  The  light  is  caught  on  the  ground  face,  goes 
through,  strikes  the  silver  at  the  rear  surface,  and  is  reflected 
back  to  the  rough  finish.  This  has  the  effect  of  producing 
very  high  efficiency,  or,  in  other  words,  a  very  high  brilliancy 
for  a  given  amount  of  projected  light.  The  mirror  screen  is 
packed  and  shipped  in  a  permanent  frame,  and  is  all  ready 
to  install  when  received. 

A  picture  projected  upon  a  plain  lookingglass  would  not 
be  visible  to  the  eye  because  the  polished  surface  will  reflect 
to  the  eye  rays  from  all  points  so  located  that  a  line  drawn  half 
way  between  the  eye  and  the  object  and  at  right  angles  to 
another  line  drawn  from  the  eye  to  the  object  will  strike  the 
mirror.  Therefore  since  the  picture  comes  from  the  lens, 
instead  of  an  image  of  the  picture  you  merely  get  a  reflec- 
tion of  the  bright  spot  light  at  the  lens  and  an  image  of  the 
auditorium,  as  a  whole.  In  order  that  the  picture  become 
visible  on  the  screen,  it  is  necessary  that  diffuse  reflection  be 
substituted  for  direct  reflection,  or,  in  other  words,  that  the 
picture  light  be  "broken  up,"  and  this  is  accomplished  by 
grinding  the  surface  of  the  glass  to  a  dull  finish. 

The  manufacturer  claims  that  the  mirror  screen  produces 
two  ideal  results,  viz:  first,  the  surface  may,  within  reason- 
able limits,  be  made  with  either  large  or  small  peaks  and 
depressions,  so  that  for  a  wide  house  the  light  is  distributed 
at  a  wide  angle,  whereas  with  a  narrow  auditorium  it  is  con- 
centrated to  a  narrow  viewing  angle.  Second,  the  surface  is 
perfectly  dull,  without  shine,  and  as  a  consequence  only  dif- 
fuse reflection  is  present,  the  same  as  on  a  dull,  white  wall, 
therefore  a  clear-cut,  clean  picture  results. 

To  sum  up  matters  pertaining  to  the  mirror  screen,  it  may 
be  said  that  if  the  screen  be  properly  selected  with  reference 
to  local  conditions  high-class  results  should  be  obtained  by 
its  use.  It  is  costly,  but  is  in  the  nature  of  a  permanent  in- 


174  MOTION    PICTURE    HANDBOOK 

vestment,  since,  barring  highly  improbable  accident  of  break- 
age, it  :'s  to  all  intents  and  purposes  indestructible,  and  once 
installed  should  require  no  attention  whatever  for  many 
years,  except  an  occasional  cleaning,  which  is  not  at  all  diffi- 
cult and  consumes  but  little  time.  The  mirror  screen  is 
peculiarly  adapted  for  use  in  very  long  auditoriums  because  of 
the  fact  that  a  person  with  average  eyesight  will  see  a  perfect 
picture  even  when  several  hundred  feet  away  from  a  mirror 
screen. 

Transparent  Screens.— The  transparent  screen  must  be 
made  of  translucent  material,  so  that  the  machine  can  be 
placed  at  its  rear  or  back  side  and  the  picture  be  viewed  by 
the  audience  in  the  auditorium  through  the  screen.  The  image 
appears  on  both  sides  of  the  curtain,  but  appears  "backward" 
to  the  operator. 

The  film  is  placed  in  the  machine  with  the  emulsion  side  to- 
zvard  the  screen,  instead  of  toward  the  light  as  in  ordinary  pro- 
jection. 

It  is  possible  to  use  ordinary  cheese  cloth  or  thin  muslin 
for  this  purpose,  but  if  this  is  done  the  machine  must  of 
necessity  be  set  lower  than  the  screen  and  "shoot  upward," 
nor  can  such  a  screen  be  used  at  all  where  there  is  a  gallery 
in  the  theatre.  The  reason  for  this  is  that  if  any  portion  of 
the  audience  sit  in  suc'h  position  that  the  eyes  will  be  in 
line  with  any  portion  of  the  picture  and  the  lens,  they  will 
see  the  bright  lens  spot  through  the  screen. 

The  translucent  screen,  however,  breaks  up  this  bright 
spot  and  renders  it  invisible.  If  a  cloth  screen  be  used  tbe 
result  will  be  greatly  improved  if  it  is  kept  wet  with  water. 
The  best  screen  for  rear  projection  is  ground  glass,  which 
lends  itself  particularly  well  to  rear  projection,  because  there 
is  but  slight  loss  of  light,  and  furthermore  the  surface  may 
be  ground,  fine  or  coarse  as  desired,  in  order  to  distribute  at 
wide  or  narrow  angles  for  a  wide  or  narrow  house.  A  fairly 
satisfactory  transparent  screen  is  made  from  tracing  cloth, 
the  worst  difficulty  being  that  it  cannot  be  obtained  suffi- 
ciently wide,  and  must  of  necessity  contain  a  seam,  which 
will  show  more  or  less  in  the  picture  in  spite  of  anything 
one  can  do. 

Rear  projection  is,  however,  not  very  much  used.  It  pre- 
sents advantages  where  conditions  are  such  that  it  can  be 
used  properly,  but  in  four  cases  out  of  five  where  it  is  at- 
tempted there  is  too  short  a  throw  to  get  the  best  results. 
In  fact  it  is  usually  employed  as  a  makeshift.  Properly 
used,  that  is  to  say  where  the  distance  from  machine  to 


FOR   MANAGERS    AND   OPERATORS  175 

screen  will  be  such  that  an  objective  lens  of  not  less  than  4 
inch  E.  F.  will  be  required,  rear  projection  on  a  glass  or 
other  high-class  translucent  screen  comes  pretty  near  being 
ideal,  since  the  operating  room,  with  its  noise,  heat  and  fire 
risk,  is  located  entirely  away  from  the  audience,  and  pre- 
sumably outside  the  theatre. 

If  this  be  done,  and  the  operating  room  be  located  in  a 
separate  structure,  it  will  be  necessary  to  locate  the  screen 
in  an  opening  in  the  theatre  wall,  and  this  opening  must  be 
protected  by  a  sheet  of  plate  glass,  outside  the  screen,  with 
the  space  between  it  and  the  screen  closed  in  tightly  to  form 
a  dead  air  space.  Otherwise  there  is  apt  to  be  trouble  with 
frost  in  winter.  It  is  also  necessary  to  protect  the  light  ray 
from  rain  and  snow  if  it  shoots  across  an  open  air  space. 
Rear  projection  is  seldom  employed  under  these  conditions, 
however. 

The  question  is  often  asked  of  the  writer:  Can  we  locate 
a  transparent  screen  at  the  proscenium  line,  set  the  projec- 
tor at  the  rear  of  the  stage  and  get  a  good  picture?  The 
answer  is  no!  It  is  never  advisable  to  attempt  the  projection 
of  a  picture  of  a  size  suitable  for  theatre  work  with  less  than 
50  feet  from  lens  to  screen,  and  40  feet  may  be  considered 
as  an  absolute  minimum,  understanding,  however,  that  really 
high-class  results  cannot  be  had  at  40  feet  unless  the  picture 
be  much  smaller  than  is  suitable  for  a  theatre.  Another 
objection  to  this  plan  is  that  it  brings  the  front  seats  too 
close  to  the  screen. 

Eye  Strain. — About  thirty-five  people  in  every  hundred 
avoid  the  picture  theatre  either  on  account  of  eye  strain  or  be- 
cause they  fear  injury  to  their  eyes.  Eye  strain  in  moving 
picture  theatres  may,  broadly  speaking,  be  attributel  to  four 
causes. 

First  (and  greatest) :  Flicker  and  Unsteady  Light. —  In  this 
case  the  retina  of  the  eye  expands  and  contracts  so  rapidly, 
in  attempting  to  adapt  itself  to  the  changing  light  intensity 
of  the  screen,)  that  the  muscles  of  accommodation  are  sub- 
jected to  terrific  strain.  This  sort  of  eye  strain  is  so  obvious 
and  so  well  understood  that  comment  seems  almost  unneces- 
sary. As  light  becomes  stronger  or  weaker  the  pupil  of  the 
eye  expands  or  contracts.  It  is  nature's  way  of  regulating 
the  amount  of  light  reaching  the  retina  of  the  eye.  When 
this  change  occurs  continuously  and  rapidly,  however,  the 
strain  is  highly  injurious.  In  this  connection  it  may  be  said 
that  in  nine  cases  out  of  ten  where  there  is  an  objectionable 


176  MOTION    PICTURE    HANDBOOK 

flicker  it  can  be  eliminated,  or  at  least  very  greatly  reduced, 
if  the  operator  understands  his  business,  and  is  able  to  match 
his  shutter-setting  and  width  of  blades  to  local  conditions. 
The  screen  itself,  as  such,  never  produces  flicker,  but  where  a 
screen  of  comparatively  low  efficiency  is  used  and  a  screen  of 
the  same  area  but  of  higher  efficiency  is  installed  using  the 
same  amperage,  this  tendency  to  flicker  will  be  increased  by  rea- 
son of  the  added  brilliancy  of  the  light.  The  period  of  dark- 
ness remains  the  same,  but  the  light  is  much  more  brilliant, 
hence  there  is  increased  contrast.  If  the  brilliancy  of  the 
picture  were  reduced  to  its  former  value  by  cutting  down 
the  amperage,  it  would  be  found  that  the  flicker  would  be 
neither  greater  nor  less  than  it  was  before. 

It  may  be  stated  as  a  fact,  that,  in  this  day  of  improved  pro- 
jection apparatus,  a  pronounced  flicker  is  inexcusable.  Either 
there  is  something  wrong  with  the  knowledge  of  the  operator, 
with  the  condition  the  projector  is  working  under,  or  the  speed 
of  projection  is  too  slow. 

Second:  Eye  strain  may  be  and  is  caused  by  lack  of  defi- 
nition in  the  picture,  which,  in  turn,  may  be  due  to  a  dirty 
lens,  a  badly  matched  lens  system,  or  to  a  poor  objective, 
to  poor  condenser,  or  to  fault  inherent  in  the  film  itself.  On 
this  account  it  is  of  very  great  importance  that  lenses  of  good 
quality  be  used,  that  they  be  kept  perfectly  clean,  and  that 
the  operator  have  his  picture  in  absolute  focus  at  all  times. 
It  is  also  important  that  manufacturers  send  out  no  film 
which,  through  inherent  fault,  cannot  be  projected  with  per- 
fect sharpness.  See  Page  152. 

Third:  Eye  strain  will  be  caused  by  poorly  illuminated,  in- 
distinct or  jumping  pictures.  An  intensely  absorbing  picture 
story  will  cause  the  audience  to  strain  every  effort  to  catch 
every  phase,  every  word,  every  expression  of  the  face  and 
action  of  the  artist  on  the  screen.  Sometimes  an  apt  expres- 
sion, though  slight  in  detail,  will  change  the  entire  meaning 
of  what  the  actor  seeks  to  portray.  We  try  to  see,  and,  by 
reason  of  dimness  or  "jumpiness"  of  this  film,  strain  our  eyes 
iti  the  effort. 

We  read  the  picture  story  just  as  zve  do  a  book,  and  if  we 
attempt  to  read  a  book  in  poor  light  or  when  it  is  shaking  or 
moving,  the  result  is  strain  upon  the  eye,  which  is  entirely  avoid- 
able by  simply  moving  into  a  better  light  and  holding  the  book 
still.  This  is  only  a  matter  of  plain  common  sense,  and  needs 
no  argument  in  its  support. 

Precisely  the  same  thing  applies  in  projection,  only  instead  of 
"moving  into  better  light"  we  get  the  same  effect  by  project- 


FOR    MANAGERS    AND   OPERATORS  177 

ing  more   light  to  the   screen,   and   instead   of   "holding  the 
book  still"  we  prevent  the  film  from  jumping. 

Fourth:  Eye  strain  is  often  caused  by  the  use  of  too  large 
a  screen,  with  a  portion  of  the  seats  placed  too  near  it.  For 
example:  we  breathe  by  unconscious  motion,  exactly  as  the 
eyt  automatically  changes  its  position  to  focus  itself  upon  the 
exact  point  we  wish  to  see,  without  any  special  mental  effort 
on  our  part.  If  we  sit  near  a  large  screen*  the  eye  will 
naturally  try  to  follow  the  film  story,  and  in  so  doing  will 
move  all  over  the  surface  of  the  screen,  moving  continuously 
and  very  rapidly.  Just  imagine  the  gymnastics  the  eye  is 
called  upon  to  perform  under  such  conditions.  I  venture  the 
assertion  that  a  glass  eye  would  not  stand  up  very  long  under 
that  sort  of  treatment,  much  less  the  delicate  organism  of  the 
human  eye. 

Flat  Surfaces— Location.— It  goes  without  saying  that  what- 
ever the  surface  of  the  screen  be  composed  of  it  should  be 
perfectly  true  and  flat,  without  wrinkles,  bumps  or  uneven 
places;  also  it  should  be  set  as  nearly  as  possible  with  its 
center  level  with  and  in  line  sidewise  with  the  lens.  This 
latter  condition  is  not  always  practical  of  accomplishment,  nor 
is  an  angle  of  projection  which  does  not  exceed  25  per  cent 
(3  inches  to  the  foot  or  IS  inches  in  60)  very  seriously 
objectionable,  though  a  side  throw  is  highly  so. 

The  practice  of  some  large  houses  in  placing  the  projection 
machine  at  the  top  of  a  very  high  gallery  and  angling  down 
at  about  45  degrees  toward  the  screen  is  a  very,  very  bad 
one.  It  causes  keystone  effect,  and,  even  allowing  that  this 
may  be  eliminated  by  filling  in  the  machine  aperture,  the 
distortion  of  the  picture  is  still  there  and  is  not  pleasing  to 
the  eye.  Many  attempt  to  compensate  for  this  by  leaning 
the  top  of  the  screen  back  a  little,  but  if  it  is  leaned  much 
more  than  twelve  inches  from  the  perpendicular  the  appear- 
ance is  unsatisfactory,  especially  from  the  main  floor.  Locat- 
ing the  operating  room  thus  wrongly  is  usually  due  directly 
to  the  fact  that  the  exhibitor  refuses  to  sacrifice  seating 
space  on  the  main  floor  in  a  lower  balcony.  He  prefers  the 
permanent  injury  of  his  projection  to  the  sacrifice  of  a  few 
seats.  The  operating  room  could  usually,  by  proper  plan- 
ning, be  placed  in  a  lower  balcony  or  even  on  the  main  floor. 
The  gain  in  excellence  of  projection  would  far  more  than 
compensate  for  the  few  seats  lost.  Its  exterior  walls  could 
easily  be  decorated  in  such  manner  that  its  appearance  would 
not  be  at  all  objectionable,  and,  in  general,  as  I  have  said,  the 
results  would  be  far  more  satisfactory. 


178  MOTION    PICTURE    HANDBOOK 

Tinted  Screen  Surfaces.— At  this  writing  (last  half  of  1915) 
it  is  very  much  the  fashion  for  screen  manufacturers  to  tint 
the  surface  of  their  screens.  Some  manufacturers  put  out 
several  surfaces,  such  as  plain  metallic,  flesh  tint,  faint 
yellow,  etc.  The  author  is  not  in  accord  with  this  practice. 
While  freely  granting  that  tinting  the  surface  of  the  screen 
may  and  probably  will  have  the  effect  of  softening  the  tone 
of  the  picture,  still  he  does  not  believe  there  is  anything  so 
beautiful  *as  the  plain  black  and  white  projection,  with  a 
pure  white  light  and  as  nearly  as  possible  a  pure  white 
screen  surface.  The  only  tinting  he  believes  in  is  the  ad- 
dition of  a  little  blue  to  the  white  when  mixing  a  screen 
paint  or  calcimine,  this  being  for  the  purpose  of  rendering 
the  white  paint  still  more  white,  just  as  the  laundryman  adds 
bluing  to  the  rinsing  water  in  order  to  make  the  clothes 
more  white.  You  will  therefore  see  that  this  sort  of  tinting 
simply  follows  out  the  author's  idea  of  making  the  screen 
as  white  as  it  is  possible  to  get  it. 

Let  it  be  noted,  however,  that  I  am  willing  to  give  due 
credit  to  the  ideas  and  opinions  of  others,  and  in  this  matter 
simply  express  my  own  individual  opinion. 

Outlining  the  Picture. — It  is  wonderful  what  a  difference 
in  effect  is  produced  by  giving  the  picture  a  proper  border 
or  outline.  There  is  nothing  so  effective  for  this  as  a  soft, 
velvety  black,  such  as  is  produced  by  ordinary  dry  lamp- 
black, mixed  with  one-third  linseed  oil  and  two-thirds  tur- 
pentine. This  form  of  outline  is  shown  in  Fig.  69.  In 
order  to  outline  the  picture  thus  proceed  as  follows:  Get  the 
light  from  both  machines  registered  on  the  screen  exactly 
where  you  want  it,  and  then  with  the  plain  white  light  pro- 
jected to  the  screen  draw  a  pencil  line  about  2  inches  inside 
the  light  all  around,  making  the  corners  round,  just  as  the 
light  is  on  the  screen.  Now  shut  off  the  light  and  paint 
all  the  screen  on  the  outside  of  the  line  black.  This  sort  of 
outline  adds  very  greatly  to  the  brilliancy  of  the  picture. 

Where  the  black  border  is  used  there  is  not  only  less 
distraction  for  the  eye,  but  the  effect  of  added  light  brill- 
iancy is  'had  without  its  actuality.  This  is  of  very  distinct 
advantage,  since  every  increase  in  actual  light  brilliancy 
has  a  tendency,  to  accentuate  any  tendency  there  may  be  to 
flicker.  With  very  brilliant  light  and  normal  speed  of  the 
projector,  even  the  more  modern  three-wing  shutters  do  not 
entirely  get  rid  of  the  flicker.  By  the  use  of  a  black  outline 
the  picture  appears  much  more  brilliant,  owing  to  contrast, 


FOR    MANAGERS    AND    OPERATORS 


179 


whereas  it  actually  remains  exactly  as  it  was,  and  thus  the 
effect  of  added  brilliancy  is  attained  without  flicker  increase. 

The  black  border  cannot  be  used,  however,  where  a  stere- 
opticon  picture  having  a  height  greater  than  the  height  of 
the  moving  picture  is  to  be  projected  on  the  same  screen; 
also  it  must  be  remembered  that  the  paint  for  the  border  must 
be  dull  black — without  any  gloss  at  all. 

The  reason  for  allowing  the  picture  to  lap  over  on  the 
black  is  that  it  greatly  minimizes  the  effect  of  any  movement 


Figure  69. 

of  the  picture  on  the  screen;  also  it  hides  any  vibration 
there  may  be  in  the  machine  aperture  itself.  Such  vibration 
should  not  be  present,  but  sometimes,  owing  to  a  poorly 
constructed  operating  room  floor,  it  is. 

Where  the  screen  is  set  back  on  the  stage  the  better  plan 
is  to  outline  the  screen  with  black,  as  above  set  forth,  and 
then  from  its  outer  edge  stretch  black  cloth  having  a  per- 
fectly dull  finish  (velvet  is  best,  though  rather  expensive), 
to  the  inside  edge  of  the  proscenium  wall  on  both  sides  and 
above,  thus  forming  a  sort  of  funnel.  If  rightly  done,  the 
cloth  preferably  being  in  pleats  or  folds  it  is  very  effective, 


180  MOTION    PICTURE    HANDBOOK 

and  sets  off  the  picture  splendidly.    The  stage  floor  in  front 
of  the  screen  should  also  be  painted  dull  black. 

Black  may  be  objected  to  as  too  somber  and  there  is  foun- 
dation for  this  objection.  Black,  however,  is  best  from  the 
projectional  point  of  view,  but  other  dark  colors  may  be  sub- 
stituted, such  as  green,  violet,  lavender  or  old  gold,  and  instead 
of  forming  a  funnel  a  more  or  less  elaborate  arrangement  or 
stage  setting  may  be  preferred.  In  fact  the  possible  combina- 
tions are  limitless,  but  stick  to  dark  colors,  with  at  least  a  two 
foot  band  of  dead  black  next  the  picture. 

Locating  the  Screen  in  Front  of  the  House,  that  is  to  say, 
at  the  end  where  the  audience  enters,  ivith  the  operating  room 
at  the  rear  end  of  the  auditorium,  is  bad  practice,  and  unless 
required  by  local  law  should  not  for  one  moment  be  considered. 
The  effect  is  bad  in  every  zvay. 

Those  entering  and  going  out  must  perforce  pass  beside 
the  screen,  which  has  the  effect  of  constantly  distracting  at- 
tention from  the  picture.  The  idea  which  has  caused  the 
lawmakers  of  some  localities  to  enact  ordinances  requiring 
this  sort  of  screen  location  is  based  on  the  view  that  in  case 
of  fire  in  the  operating  room  the  audience  will  not  be  obliged 
to  pass  near  it  and  therefore  will  not  become  panic-stricken. 
That  argument  sounds  very  nice;  also  it  looks  well  in  print.  The 
only  fault  that  could  possibly  be  found  with  it  is  that  it 
doesn't  work  out  in  practice.  If  an  operating  room  fire  occurs 
with  the  operating  room  near  the  entrance  of  the  theatre 
the  audience  hestitates  to  some  extent  to  pass  it,  and  is, 
to  just  that  extent,  deterred  from  making  a  rush,  but  if  the 
operating  room  is  located  at  the  other  end  and  a  fire  occurs, 
good  night!  Somebody  yells  fire:  There  is  nothing  in  the 
world  to  stop  them.  They  make  one  grand  rush  and  pile 
up  in  a  heap  at  the  entrance.  Result:  many  injured,  and  prob- 
ably some  killed.  There  is  no  earthly  necessity  for  such 
laws,  anyway.  If  the  operating  room  be  rightly  constructed, 
equipped  with  a  proper  vent  flue  and  has  a  properly  ar- 
ranged shutter  system,  you  can  burn  several  reels  of  film 
therein  and  the  audience  will  never  know  there  is  a  fire. 
//  our  distinguished  lawmakers  would  pay  more  attention  to  the 
proper  arrangement  of  the  vent  flue  and  fire  shutters  of  the 
operating  roomt  and  not  so  much  to  foolish  ideas  of  this  sort, 
it  would  be  much  better  for  all  concerned. 

Where  the  screen  is  located  on  the  stage  and  the  house 
is  a  short  one,  say  less  than  75  feet  in  depth,  it  is  much 
better  to  set  the  screen  back  as  far  as  you  can  get  it  without 


FOR   MANAGERS    AND   OPERATORS  181 

seriously  interfering  with  the  view  from  extreme  side  seats. 
Those  in  the  rear  will  still  be  close  enough  to  have  an  ideal 
view,  while  those  in  the  front  rows  and  at  the  side  of  the 
auditorium  will  have  a  vastly  improved  view  over  what  it 
would  be  if  the  screen  was  at  the  proscenium  line. 

Where  Vaudeville  Is  Used. — In  many  theatres  where  a 
mixed  performance  is  given  it  is  necessary  that  the  screen  be 
placed  near  the  curtain  line,  in  order  that  the  stage  may  be 
set  while  the  picture  is  being  run.  The  majority  of  houses 
of  this  kind  use  a  plain  cloth  drop,  usually  outlined  in  black. 
Such  a  screen  will  sway  with  every  breeze,  or  will  move 
when  touched  by  stage  hands  working  at  its  rear.  A  much 
better  plan  would  be  to  frame  this  drop  substantially,  though 
lightly,  and  back  it  with  light  lumber.  At  either  side 
grooves  can  be  arranged  so  that  the  screen  will  always  set 
precisely  in  the  same  spot  when  lowered,  and  will  at  all 
times  be  perfectly  flat.  All  this  is  entirely  practical,  and 
should  be  carried  out,  though  it,  of  course,  applies  only  to 
houses  having  a  fly  loft.  Such  a  screen  would  be  tolerably 
heavy,  but  could  easily  be  counterweighted  to  handle  with 
perfect  ease. 

Height  Above  the  Floor.— The  height  of  the  screen  above 
the  floor  must  be  governed  by  circumstances,  but  where 
there  is  a  stage  I  believe  the  general  effect  is  best  if  the 
bottom  of  the  picture  be  located  quite  near  the  stage  floor. 
True,  there  is  a  distinct  advantage  in  locating  the  picture 
high  up  on  the  wall,  since  it  does  away  with  the  obstruction 
to  the  view  caused  by  persons  seated  in  front.  Such  a 
location,  however,  also  has  serious  disadvantages,  which, 
in  my  opinion,  far  more  than  outweigh  the  gain.  The 
disadvantage  is  that  the  picture  is  not  shown  in  the  normal 
level  position  in  which  we  are  accustomed  to  look  at  such 
scenes  in  real  life.  It  has,  I  think,  a  decided  tendency  to 
emphasize  in  our  mind  the  fact  that  we  are  looking  at.  a 
picture,  and  not  a  real  performance.  Everything  considered, 
I  believe  that  locating  the  bottom  of  the  picture  at  as  nearly 
as  practical  six  feet  above  the  auditorium  will  usually  be 
best. 

Size  of  Picture. — Much  has  been  said,  and  many  arguments 
have  been  advanced  for  and  against  the  large  and  the  small 
picture.  The  question  is  just  as  strongly  debated  today  as 
it  ever  was.  Personally,  I  do  not  believe  there  is  or  ever  will 
be  any  set  rule  as  to  the  picture  size  which  can  always  be 
followed  to  advantage.  The  photograph,  as  projected  through 


182  MOTION    PICTURE   HANDBOOK 

the  machine  aperture,  has  very  considerably  less  than  one 
square  inch  of  area.  We  therefore  see  that  the  magnifica- 
tion is,  in  any  event,  enormous,  and  we  must  remember  that 
Every  defect  in  photography,  every  movement  of  the  film,  and 
every  scratch  mark  and  jump  is  magnified  as  the  size  of  the 
picture  is  increased.  Also  we  must  remember  that  as  the  size 
of  the  picture  is  increased  the  light  strength  must  also  be  rapidly 
increased,  if  the  brilliancy  of  picture  is  to  remain-  as  it  was. 

You  have  a  light  strength  produced  by  30  amperes  D.  C., 
let  us  assume.  You  are  projecting  a  12  foot  picture.  This 
means  that  the  light  is  distributed  over  108  square  feet  of 
area.  Suppose  you  increase  the  size  to  16  feet.  You  now 
have  192  square  feet  of  surface — almost  double  that  of  the 
12  foot  picture;  hence  the  curtain  brilliancy  obtained  from 
your  light  is  decreased  by  almost  one  half.  You  must  in- 
crease the  amperage  very  greatly  to  secure  illumination 
equal  to  that  of  the  12  foot  picture.  You  will  therefore  see 
that  a  large  picture  is  costly,  in  current  consumption  or  in 
sacrifice  of  brilliancy.  See  Page  165.  A  12  foot  picture  is  con- 
sidered as  being  "life  size."  A  picture  of  this  size  is,  to  one  of 
normal  vision,  perfectly  distinct  in  all  its  details  75  or  even 
100  feet  away,  or  much  further  if  it  be  a  mirror  screen.  It 
is  seldom  there  is  any  real  reason  for  projecting  a  larger 
picture,  so  far  as  ability  of  the  audience  to  see  the  details 
of  the  picture  b£  concerned.  It  must,  however,  be  granted 
that  in  a  large  house  a  12  foot  picture  seems  somewhat  out 
of  proportion,  especially  if  the  screen  be  located  on  a  large 
stage. 

One  other  very  important  factor  enters,  viz:  ability  of 
those  in  the  rear  seats  clearly  to  see  the  faces  of  the  actors, 
this  by  reason  of  the  fact  that  in  the  silent  drama  very  much 
often  depends  upon  facial  expression.  The  glance  of  an  eye 
or  some  movement  of  the  features  may  change  the  whole 
meaning. 

However,  again  no  rule  can  be  given  which  will  apply  to 
all  cases.  With  a  high  grade  lens  and  a  perfectly  sharp, 
brilliant  picture  these  things  are  clearly  discernible  under 
conditions  which  would  render  them  almost  invisible  with 
weak  light  or  poor,  "fuzzy"  definition. 

The  size  may  be  increased  very  greatly,  but  it  is  always 
at  the  expense  before  mentioned.  The  possible  limit  depends 
on  local  conditions,  and  how  much  you  are  willing  to  expend 
for  current  and  good  lenses;  also  mirror  screens  do  not  ex- 
ceed 13^2  by  \8l/2  feet  in  size.  For  a  throw  of  50  feet,  fifteen 
feet  ought  to  be  the  limit,  since  with  a  wider  picture  optical 


FOR    MANAGERS    AND   OPERATORS  183 

difficulties  are  encountered.  A  very  short  focal  length  pro- 
jection lens  is  required  to  project  a  wide  picture  on  a  short 
throw,  and  such  lenses  seldom  give  sharp  definition.  With 
a  throw  of  75  feet,  an  18-foot  picture  is  as  large  as  it  is 
well  to  attempt.  At  100  feet  almost  any  size  you  can  illumi- 
nate may  be  projected.  To  put  the  matter  concisely,  I  do 
not  advise  the  use  of  a  projection  lens  of  less  than  4  inch 
equivalent  focus.  This  matter  will,  however,  be  treated 
more  exhaustively  under  "Lenses."  Mr.  Frank  Rembusch, 
who  has  made  a  study  of  such  matters,  says : 

"If  a  screen  is  too  large,  an  elongation  of  faces  and  figures 
results,  especially  on  a  short  throw,  where  the  house  is  short. 
If  the  screen  is  too  small  the  results  also  are  not  satisfactory. 
To  some  extent,  of  course,  it  is  a  matter  of  taste,  but  after 
consulting  the  best  authorities,  together  with  inquiries  among 
lens  manufacturers  as  to  what  can  be  done,  I  have  arrived 
at  the  following  opinion:  A  house  25  feet  wide  and  75  feet 
long  should  have  a  screen  about  9  feet  by  12  feet,  and  the 
longer  or  wider  house  in  this  proportion.  For  instance,  a 
house  40  feet  wide  and  100  feet  long  should  have  about  a 
12  by  16  screen;  a  house  25  feet  wide  and  125  feet  long  should 
have  about  an  11.6  by  15.4  screen.  No  screen  should  be 
larger  than  12  by  16,  except  where  the  first  row  of  seats  in  • 
front  can  be  located  at  least  30  feet  distant  therefrom, 
and  the  throw  is  not  less  than  125  feet.  Here  is  your  limit. 

"A  larger  screen  will  cause  eye  strain  up  close,  and  with  a 
shorter  throw  will  cause  elongation  of  the  faces  and  figures,  and 
a  distortion  of  the  pictures." 

Certainly  friend  Rembusch  is  rather  extreme  in  his  state- 
ment that  it  is  not  well  to  attempt  the  projection  of  a  pic- 
ture larger  than  16  feet  at  less  than  125  feet.  I  am  of  the 
opinion  that  a  practically  perfect  18-foot  picture  may  be 
projected  at  100  feet  (5%  inch  E.  F.  lens),  or  even  a  little 
less.  His  other  statements  I  agree  with,  however. 

Coatings. — Many  managers,  particularly  in  the  smaller 
towns,  and,  to  some  extent  in  the  small  theatres  of  the 
larger  cities,  prefer  to  use  a  home-made  screen,  which  they 
construct  of  cloth,  plaster,  and  occasionally  of  metal.  I  have 
already  set  forth  the  relative  points  of  excellence  as  between 
the  cloth,  plaster,  metallized  and  mirror  surfaces,  to  which 
I  will  add  the  further  remark  that  cloth,  or  plaster  properly 
coated,  gives  as  artistic  a  projection  as  it  is  possible  to 
produce  on  any  surface.  The  difference  between  it  and  the 
more  costly  screen  is  found  in  the  fact  that  with  the  latter 


184  MOTION    PICTURE    HANDBOOK 

surfaces  much  greater  brilliancy  is  had  for  a  given  amperage 
than  is  possible  with  either  cloth  or  plaster. 

The  traveling  exhibitor,  as  a  general  proposition,  uses  an 
uncoated  cloth  "sheet,"  but  where  cloth  is  used  in  a  perma- 
nent location  it  should  be  stretched  very  tightly  on  some  sort 
of  frame,  coated  with  a  size  made  by  dissolving  a  good 
grade  of  glue  in  warm  water.  I  do  not  remember  the  exact 
amount,  but,  at  a  guess,  would  say  about  one  pound  of  good 
glue  to  an  ordinary  pailfull  of  water.  When  the  sizing  is 
thoroughly  dry  the  screen  may  receive  its  final  coating, 
which  may  be  (a)  white  lead  or  zinc  ground  in  oil  (to  be  had 
at  any  paint  store),  mixed  about  in  the  proportion  of  one- 
fourth  boiled  linseed  oil  and  three-fourths  turpentine,  to 
which  has  been  added  just  a  little  ultramarine  or  prussian 
blue — not  much,  but  just  enough  to  give  the  paint  a  rather 
pronounced  bluish  tint  while  in  the  pot.  It  will  look  per- 
fectly white  on  the  screen,  (b)  One  of  the  patent  white 
calcimines,  such  as  muralite,  alabastine,  etc.,  also  to  be  had 
at  any  paint  store.  No  matter  whether  paint  or  calcimine 
is  used  give  the  curtain  two  or  three  coats,  rather  than  one 
heavy  one,  and  be  sure  there  are  no  brushmarks  when  the 
job  is  finished.  After  the  final  coat  has  dried,  outline  the 
screen  in  black,  as  already  directed.  See  Page  178. 

Where  a  plaster  screen  is  used  I  would  recommend  that 
it  be  of  cement  finish,  rather  than  ordinary  hard  coat,  be- 
cause the  cement  may  be  calcimined  and  the  calcimine 
washed  off  and  renewed  many  times  without  in  any  way 
affecting  the  underlying  surface.  The  plaster  or  cement 
should  be  coated  with  one  of  the  patent  calcimines  as  before 
mentioned  even  though  the  surface  be  plaster.  The  cal- 
cimine will  give  a  considerable  better  projection  surface 
than  will  the  plaster  itself. 

Caution. — Do  not  imagine  you  can  coat  a  cloth  or  plaster 
screen  with  calcimine  or  paint  and  use  it  indefinitely  without 
doing  anything  more  to  it. 

I  would  very  strongly  recommend  that  where  a  plaster 
calcimine  coated  screen  is  used,  it  be  washed  off  and  re- 
coated  at  least  once  every  sixty  days.  It  may  look  clean  and 
bright,  but  you  may  take  it  from  me,  it  is  not.  The  wall  paper 
or  calcimine  on  the  ceiling  of  your  home  may  look  perfectly 
clean,  but  rub  your  damp  finger  on  it  and  see  if  it  is;  per- 
haps the  result  will  astonish  you.  The  same  thing  applies  to 
the  screen.  Calcimine  is  cheap.  My  advice  is  to  USE  IT  FRE- 
QUENTLY. 


FOR   MANAGERS    AND   OPERATORS  185 

Paint  may  be  washed,  if  it  is  carefully  done,  but  it  is  not 
the  same  as  new.  I  much  prefer  calcimine  to  paint  on  a 
plaster  surface,  but  if  paint  is  used,  the  plaster  should  be  first 
thoroughly  sized. 

Caution. — Don't  attempt  to  make  home-made  metal  surface 
screens  by  applying  aluminum  to  cloth  or  plaster.  There  is 
about  one  chance  in  a  hundred  that  you  will  get  anything  even 
approaching  satisfactory  results.  Calcimine  or  paint  is  much 
better  than  ninety-nine  out  of  every  hundred  home-made  alu- 
minum screens. 

THE  DIFFERENT  SCREENS 

The  Mirror  Screen. — The  salient  points  concerning  the 
niirror  surface  made  by  the  Mirror  Screen  Company,  Shelby- 
ville,  Ind.,  have  already  been  set  forth.  The  screen  is  a 
high  class  article,  and  has  many  enthusiastic  suporters  among 
exhibitors.  It  gives  a  very  brilliant  picture  per  ampere  of 
current  used.  It  is  expensive  in  first  cost,  but  will  last 
practically  forever.  The  surface  must  be  very  carefully 
selected  with  reference  to  the  conditions  under  which  it  is  to 
work.  For  the  long,  narrow  house,  get  a  smooth  finish,  but 
for  a  wide  house  get  it  just  as  rough  as  possible.  It  comes 
all  packed  in  a  box,  ready  for  installation.  Its  surface  can  be 
washed  perfectly  in  a  few  moments.  The  silver  backing  is 
guaranteed  against  deterioration. 

There  are  nine  different  mirror  screen  surfaces,  designed 
for  use  in  theatres  of  varying  dimensions.  Mirror  screens 
have  been  in  use  in  theatres  for  several  years.  Therefore 
they  have  been  thoroughly  tested  as  to  their  efficiency,  and, 
as  already  stated,  when  properly  selected  with  reference 
to  local  conditions  results  from  them  are  excellent.  They 
may  be  had  in  the  following  widths:  8  feet,  8  feet  8  inches, 
9  feet  4  inches,  10  feet  8  inches,  11  feet  4  inches,  12  feet, 
12  feet  8  inches,  13  feet  4  inches,  14  feet,  14  feet  8  inches, 
15  feet  4  inches,  16  feet,  16  feet  8  inches,  17  feet,  17  feet  4 
inches,  17  feet  8  inches,  and  18  feet.  The  last  four  widths 
require  slot  cars  for  their  shipment.  They  are  made  as  small 
as  required,  but  8  feet  is  about  the  minimum  used  in  theatri- 
cal work. 

When  exhibitors  erect  a  theatre  and  contemplate  installing 
a  mirror  screen  they  should  remember  that  the  screen  must 
be  brought  in  before  the  walls  are  closed  in,  as  it  is  all  in 
one  piece.  The  8-foot  screen  is  6  feet  high,  with  probably 
a  foot  added  to  that  for  packing,  and  in  an  old  house  it  may 


186  MOTION    PICTURE    HANDBOOK 

be  necessary  to  cut  a  slot  in  the  wall,  over  a  door  or  else- 
where, to  get  a  mirror  screen  in. 

The  prices  range  from  $135  for  an  8-foot  screen  to  $1,000 
for  the  18  footer. 

The  same  company  also  manufactures  metallic  surface 
screens  of  various  kinds,  made  of  seamless  cloth,  and  the 
surface  is  guaranteed  against  deterioration  for  a  period  of 
five  years. 

Simpson  Solar  Screen. — One  of  the  oldest  metallic  surface 
screen  surfaces  on  the  market  is  the  Simpson  Solar  Screen, 
manufactured  by  the  Simpson  Solar  Screen  Company,  New 
York  City.  This  surface  is  of  pure,  carefully  selected  alumi- 
num. Each  screen  is  hand-made,  and  the  surface  thus  pro- 
duced gives  sharp  contrast  as  between  the  whites  and  blacks; 
also  it  gives  great  brilliancy  to  the  whites. 

The  screen  is  made  in  one  piece  up  to  twelve  feet  in  width. 
The  author  can  vouch  for  the  excellence  in  results  from  this 
surface.  It  is  guaranteed  against  peeling,  tarnishing  or  other 
defect  for  a  period  of  five  years,  and  its  manufacturers  assure 
me  that  the  guarantee  will  be  made  good. 

The  surface  is  slightly,  though  not  heavily  matte.  The 
reflection  is  entirely  diffuse,  there  being  no  direct  reflection, 
therefore  no  haze. 

The  Mirroroid  Screen.— The  J.  H.  Center  Company,  New- 
burgh,  N.  Y.,  manufactures  the  mirroroid  screen,  which  is  a 
product  familiar  to  exhibitors  pretty  much  all  over  the  coun- 
try. Mirroroid  screens  have  a  matte  surface.  The  com- 
parative matte  of  the  various  mirroroid  surfaces  is  shown 
in  Fig.  70,  which  is  a  full  size  photograp'h  of  samples  of 
the  material.  In  the  opinion  of  the  writer  the  rough  surfaces 
are  best  adapted  for  use  in  wide  houses,  and  it  is  his  opinion 
that,  w.hereas  the  matte  or  visible  roughness  of  the  surface 
has  little  or  nothing  to  do  with  the  actual  diffusion  of  light, 
still  it  has  a  very  beneficial  effect  in  enabling  the  spectator 
who  views  the  picture  at  a  side  angle  to  get  a  good  detail 
of  the  picture.  There  is  a  distinct  difference  in  the  effect 
produced  by  the  visible  roughness  of  the  matte  surface, 
and  in  the  effect  produced  by  the  invisible  peaks  and  de- 
pressions before  described.  One  produces  light  diffusion  and 
the  other  gives  detail  to  the  picture  when  viewed  from  an 
angle,  or,  at  least,  that  is  my  opinion.  Each  is  of  impor- 
tance to  perfect  projection. 

Mirroroid  screens  have  given  very  general  satisfaction, 
and  can  be  recommended  to  the  consideration  of  exhibitors 
who  are  looking  for  a  good  article.  They  come  in  a  variety 


FOR   MANAGERS    AND   OPERATORS 


187 


of  tints,  such  as  plain  "metallic  surface,"  "silver  white," 
"flesh"  tint,  etc.,  and  the  surfaces  are  guaranteed  against 
deterioration  for  a  period  of  five  years.  They  are  seamless 
up  to  about  11  feet  wide  and  above  that  a  special  treatment 
tends  to  render  the  seam  invisible. 


Figure  70. 


The  Minusa. — The  Minusa  Cine  Products  Company,  St. 
Louis,  is  putting  out  various  types  of  metallic  surfaces,  its 
specialty  being  the  Minusa  Gold  Fibre  Screen.  This  com- 
pany produces  screens,  some  of  which  have  very  rough  sur- 
faces, as  shown  in  Fig.  71,  which  is  a  full  size  photograph 
of  samples  submitted  by  the  Minusa  concern.  These  screens 


188 


MOTION    PICTURE    HANDBOOK 


are  fully  guaranteed  for  a  period  of  five  years  against  de- 
fective workmanship,  discoloration,  etc. 

The  Radium  Gold  Fibre  Screen  is  one  of  the  oldest  and 
most  widely  advertised  of  the  many  so-called  "patent"  pro- 
jection surfaces.  Radium  Gold  Fibre  is  a  metallized  screen 


Figure  71. 

and  is  frankly  sold  as  such,  with  all  arguments  both  for  and 
against  the  metallized  projection  surface  kept  constantly  in 
mind  by  those  who  are  marketing  it.  A  high  grade  gold 
bronze  is  the  basic  ingredient  of  the  surface  coating,  and 
the  arguments  for  and  against  the  use  of  yellow  in  projection 
surfaces  are  well  known.  Unquestionably  the  radium  gold  is 


FOR    MANAGERS    AND   OPERATORS  189 

an  excellent  surface  for  those  who  favor  a  yellow-tinted  sur- 
face. It  is  made  by  Radium  Gold  Fibre  Screen,  Inc.,  220 
West  Forty-second  Street,  New  York. 

Stippled  Surface. — The  following  is  a  scheme  for  which  it 
seems  H.  E.  Hammond,  manager  of  the  Crescent  Theatre, 
Erie,  Pa.,  is  responsible.  It  is  a  new  one  and  I  only  give  it 
for  what  it  is  worth,  with  the  remark  that  it  looks  very 
good.  It  has  been  reported  on  favorably  by  the  operator 
who  installed  the  projection  plant  in  the  Crescent. 

Mix  dry  zinc  (to  be  procured  from  any  paint  store)  with 
water,  making  it  as  thick  as  can  be  spread  with  a  paint  brush. 
Then  paint  the  plaster  wall  with  the  mixture,  and  follow  up 
with  a  wide,  flat  brush,  pouncing  the  wet  surface  with  the 
ends  of  the  bristles  of  the  brush.  Let  it  dry  thoroughly. 
Apply  a  second  coat  and  pounce  in  the  same  manner;  let  this 
dry  and  apply  a  third  coat,  again  pouncing  with  the  brush. 
The  result  is  a  flat  surface,  covered  with  little  round  craters, 
or  depressions. 

This  ought  to  make  a  very  white  surface,  and,  moreover, 
the  effect  should  be  good.  It  is  said  that  the  picture  shows 
up  much  better  on  a  wide  view  where  this  surface  is  used. 

Chalk  Surface. — Still  another  surface  has  been  favorably 
reported.  It  has  in  its  favor  the  fact  that  it  may  be  easily 
and  cheaply  tried  out.  It  consists  of  rubbing  any  suitable 
surface  thoroughly  with  ordinary  white  chalk,  school  crayon 
broken  into  pieces  two  inches  long  and  used  flatwise  will  do, 
but  chalk  such  as  mechanics  use  for  chalk  lines  (obtainable 
at  hardware  stores)  is  much  the  best.  It  is  said,  and  it 
sounds  reasonable,  that  a  picture  projected  on  this  surface 
stands  out  with  great  brilliance.  You  must,  of  course,  get 
the  chalk  rubbed  on  evenly. 

Fire-Proofing. — Any  fabric  may  be  fire-proofed  by  thor- 
oughly saturating  it  with  ammonia  phosphate  mixed  in  the 
proportion  of  one  pound  to  one  gallon  of  water.  In  the 
case  of  a  cotton  screen  I  would  stretch  it  tightly  on  a  frame, 
dissolve  the  phosphate  in  water  and  saturate  the  fabric 
thoroughly  by  using  a  new,  cheap  paint  brush.  Let  it  dry 
and,  while  it  will  char,  it  will  not  and  cannot  be  made  to 
blaze.  A  lighted  match  would  char  the  fabric  where  it  came 
in  actual  contact  with  it,  but  that  would  be  all  there  would 
be  to  it — just  a  hole  in  the  cloth.  Phosphate  of  ammonia 
may  be  had  of  retail  druggists  at  about  75  cents  a  pound; 
wholesale  it  is  much  cheaper.  There  is  nothing  in  phosphate 
of  ammonia  that  will  injure  the  fabric.  Wood  soaked  in 


190 


MOTION    PICTURE    HANDBOOK 


Figure  72. 


this  solution  is  made  thoroughly  fire-proof  in  the  sense  that 
it  cannot  be  made  to  blaze. 

Stretching  the  Screen.— The  Mirror  Screen  Company,  which 
also  manufactures  metallic  surface  screens,  suggests  the  use 

of    a    frame    known    as 

the    "artist    frame"    for 

mounting  moving  pic- 
ture metallic  surface 
screens  or  cloth  screens. 
Some  years  ago  the 
mounting  of  a  screen 
was  of  little  importance. 
A  cloth  screen  was 
mostly  used,  and  due 
to  low  reflective  power, 
uneveness  or  wrinkles 
therein  were  scarcely 
visible;  moreover  a 
thin  cloth  could  be 
stretched  taut  on  almost 
any  kind  of  a  frame.  Of  late,  however,  the  wide  use  of  metallic 
surface  screens,  many  of  which  are  on  a  heavy  canvas,  makes 
it  necessary  though  very  difficult  to  stretch  them  tightly, 
since  with  a  semi-reflective  surface  every  wrinkle  or  uneven 
place  will  show  badly. 
There  is  nothing  bet- 
ter adapted  for  this  pur- 
pose than  what  is 
known  as  the  "artist 
frame."  It  is  much 
superior  to  any  home- 
made arrangement,  and 
may  be  purchased  from 
almost  any  screen  manu- 
facturer for  less  than  it 
would  cost  an  exhibitor 
to  make  it.  It  is  simple, 
and  I  believe  quite  satis- 
factory. It  may  be  Figure  73. 
shipped  K.  D.,  and  the 

process  of  putting  it  together  is  one  which  can  be  readily  per- 
formed by  any  man  of  ordinary  intelligence.  Begin  to  put  the 
frame  together  by  laying  it  bottomside  up,  on  a  floor  or  other 
flat  surface.  After  the  corners  are  bolted  together  see  that 


FOR   MANAGERS    AND   OPERATORS 


191 


every  corner  and  the  whole  frame  is  exactly  square.  This  may  be 
tested  by  measuring  diagonal  corners.  If  the  distance  from 
diagonally  opposite  corners  is  equal  the  screen  is  square.  Now 
put  on  the  back  braces  and  then  turn  the  frame  over  or  set  up- 
right in  place.  The  various  steps  in  the  process  are  shown,  in 
their  order,  in  Fig.  74. 

Putting  on  Cloth.— The  cloth  should  be  rolled  up  so  that 
the  edge  that  goes  to  the  top  unrolls  first.  It  may  be  put  on 
either  with  the  frame  standing  up  or  laying  down.  Standing 
the  frame  upright  is  the  best  plan,  however,  because  the 
cloth  will  partly  stretch  by  its  own 
weight,  and  the  whole  job  will  be 
more  easily  and  better  done.  A 
good  start  insures  success.  Lay 
the  roll  of  cloth  on  a  level  floor; 
unroll  a  foot  or  two,  and  stretch 
a  chalk  line  to  determine  whether 
or  not  its  edge  is  perfectly 
straight.  Trim  it,  if  necessary,  to 
fit  the  chalkline.  Now  make  a 
chalkline  across  near  the  extreme 
edge  of  the  top  of  the  frame,  on 
the  front  side,  where  the,  cloth 
is  to  be  tacked.  The  straight  top 
edge  of  the  cloth  and  the  line  on 
frame  are  placed  together,  and 
the  cloth  is  tacked  fast,  thus  in- 
suring a  good,  straight  start. 

Tacking  on  Cloth.— Place  the 
tacks  about  two  inches  apart.  A 
thin  tack  with  a  large,  flat  head 
is  the  best.  If  the  frame  is 
placed  upright  a  piece  of  cheese- 
cloth should  be  looped  and  nailed 
to  the  frame  on  each  end,  to  hold 
the  roll  of  cloth  in  position  while  the  top  edge  is  tacked  in  place. 
Start  at  the  center  of  the  top,  and  tack  both  ways  along  the  chalk 
line,  until  within  about  three  or  four  feet  of  the  corner.  A 
single  tack  will  hold  each  corner  in  position  until  you  are 
ready  to  tack  corners.  Now  unroll  cloth  slowly  and  carefully, 
keeping  it  stretched  at  all  times.  Stretch  and  tack  the  bot- 
tom of  screen,  beginning  at  center  and  working  again  to 
within  three  or  four  feet  of  each  corner.  Now  tack  one  side 
at  center  to  within  a  short  distance  of  corner,  and  then  tack 


Figure  74. 


192  MOTION    PICTURE    HANDBOOK 

and  stretch  the  cloth  on  the  other  side,  after  which  finish  up 
the  corners. 

In  tacking  any  cloth  screen  always  begin  at  centers  of  each 
side  and  finish  corners  last. 

If  the  work  is  done  carefully  the  surfaces  will  be  almost 
entirely  free  from  wrinkles,  and  where  a  light  cloth  is  used 
and  well  stretched  by  hand  a  very  even  surface  is  possible 
on  a  common  hand-made  frame.  The  artist  frame  we  arc 
describing  is  provided  with  finishing  strips  which  are  nailed 
to  cover  up  the  tacks  and  raw  edge  of  the  cloth,  and  this 
helps  the  appearance  very  much.  Beveled  stretcher  strips  are 
then  pushed  down  between  the  cloth  and  frame  from  the 
back,  giving  the  appearance  of  a  bevel  around  the  edge  on  the 
face  side.  This  gives  a  handsome,  finished  appearance  to 
the  screen  generally. 

In  most  cases  the  cloth  is  free  from  wrinkles  when  the 
stretcher  strips  are  put  in  position,  but  to  provide  for  fur- 
ther stretching  lag  bolts  are  placed  in  the  frame  which,  when 
screwed  in,  push  out  the  stretcher  strips  still  farther,  so 
that  the  screen  can  be  made  as  tight  as  a  drumhead.  The 
artist  frame  is  always  good  property,  as  it  can  be  used  again 
for  new  cloth.  Those  exhibitors  who  use  metallized  screens 
should  renew  them  at  least  every  two  years.  Many  metallic 
screen  surfaces  lose  their  brilliancy  in  even  less  time,  and 
often  those  of  inferior  quality  will  become  dull  within  a  few 
months.  Fig.  72  shows  front  of  finished  screen. 

THE  FILM 

The  film  is  a  strip  of  celluloid  \Y%  inches  wide,  by  from  Sl/2  to 
6  thousandths  of  an  inch  thick.  In  the  process  of  making 
the  celluloid  is  originally  in  strips  about  2  feet  wide  by  250  to 
300  feet  in  length.  These  wide  strips  are  passed  through  a 
machine  which  spreads  upon  one  side  a  coating  (negative  or 
positive,  according  to  the  use  to  which  the  stock  being  treated 
is  to  be  put)  of  photographic  emulsion,  approximately  one- 
thousandth  of  an  inch  in  thickness,  this  being  a  part  of  the 
thickness  of  the  film  as  above  given. 

After  having  received  its  emulsion  coating  the  film  is  run 
through  another  machine,  which  splits  it  into  ribbons  \Y%  inches 
wide,  and  these  ribbons  become  the  film  stock  which  is  pur- 
chased by  the  photoplay  producer. 

The  negative  stock  is  first  perforated  and  then,  as  needed, 
is  placed  in  a  camera  having  an  intermittent  movement,  re- 
volving shutter  and  lens  very  similar  in  action  to  those  of  the 
projection  machine  (except  that  the  mechanism  is  inclosed  in 


FOR    MANAGERS    AND    OPERATORS  193 

a  light-tight  box  or  casing),  and  each  three-quarters  of  an 
inch  of  its  length  is  successively  exposed  to  light,  and  what 
is  essentially  a  "snap  shot"  photograph  impressed  thereon  at  the 
rate  of  sixteen  per  second  (that  is  to  say  sixteen  per  second 
is  supposed  to  be  the  rate,  but  in  practice  camera  speed  varies 
considerably).  After  exposure  the  negative  is  developed,  fixed 
and  dried  much  the  same  as  any  ordinary  kodak  negative 
would  be — the  actual  mechanical  methods  differ  from  the  kodak 
film,  of  course,  as  the  negative  film  will  be  more  than  200  feet 
long,  but  the  chemical  action  is  precisely  the  same.  The  negative 
is  then  run  through  a  projection  machine  so  that  the  director 
may  check  up  his  work,  make  the  scene  over  again,  if  necessary, 
or  <cut  out  any  undesirable  portions.  When  the  negative  is 
finally  in  acceptable  form,  it  is  placed  in  a  printing  machine  in 
contact  with  a  strip  of  positive  film  (positive  and  negative 
film  are  exactly  the  same,  except  that  a  different  grade 
or  kind  of  photographic  emulsion  is  used),  and  by  means  of  an- 
other intermittent  movement  and  revolving  shutter,  but  without 
a  lens  this  time,  is  exposed  to  artificial  light  of  known  power, 
each  picture  being  exposed  for  the  small  fraction  of  a  second. 
The  positive  film  is  then  developed,  fixed  and  dried,  after  which 
it  is  sent  to  the  assembling  room,  where  the  various  scenes  con- 
stituting a  complete  photoplay  are  arranged  in  sequence,  joined 
together,  the  titles  and  sub-titles  put  in,  and  it  becomes  the 
"reel  of  film"  with  which  we  are  all  so  familiar. 

These,  very  briefly  and  crudely,  are  the  processes  a  film 
goes  through  in  the  course  of  its  making. 

The  perforating  is  usually  done  by  the  producer,  though 
perforated  stock  may  be  bought  from  the  film  stock  maker. 
There  are  64  perforations  to  the  foot  on  either  side,  or  four 
to  the  picture.  Film  perforation  is  one  of  the  most  vexing 
problems  with  which  the  producer  is  confronted.  Unless  it 
be  done  with  absolute  accuracy  there  will  be  unsteadiness, 
and  if  the  negative  be  unsteady  in  the  camera,  and  the 
positive  be  unsteady  in  the  projection  machine,  the  effect  is 
to  magnify  the  slightest  inaccuracy  in  workmanship  and 
produce  a  very  unsteady  picture  on  the  screen.  Then,  too, 
even  with  absolute  mechanical  accuracy  in  the  perforating 
room,  carelessness  in  the  drying  room  may  cause  trouble,  or 
inequality  in  thickness  of  film  stock  may  cause  uneven  shrink- 
age, and  again  there  is  unsteadiness  in  the  final  result  on  the 
screen.  It  will  thus  be  seen  that  those  producers  who  are 
giving  us  films  which  give  steady  projection  are  entitled  to 
much  credit  for  their  painstaking  care. 


194  MOTION    PICTURE   HANDBOOK 

Thickness  of  Film  Stock.— Film  stock  should  be  of  the  full 
standard  thickness,  since  thin  stock  has  decided  tendency 
to  produce  unsteadiness  of  the  picture. 

Standard  Perforations. — Perforations  should,  by  all  means, 
be  of  standard  dimensions.  Instead  of  that  there  are  several 
sizes  and  shapes,  and  since  the  projector  sprocket  teeth, 
which  engage  with  these  perforations,  are  of  necessity  of 
standard  dimensions,  more  or  less  trouble  is  encountered 
from  this  source.  At  this  time  (Dec.  15,  1915)  the  Motion 
Picture  Board  of  Trade  has  just  formed  a  "Bureau  of 
Standardization,"  the  first  work  of  which  is  expected  to  be 
the  standardization  of  film  perforations. 

Damage  to  Film. — Naturally  an  article  so  thin  and  fragile 
as  film  is  susceptible  to  .damage.  Film  is  easily  torn  in  two; 
also  it  is  easily  scratched,  particularly  the  emulsion.  Its 
sprocket  holes  are  subject  to  strain  and  to  breaking  and 
tearing.  Most  of  the  tearing  is  due  to  loose  patches  catching 
on  sprocket  idler  rollers  and  to  worn  sprocket  teeth  and 
improperly  adjusted  projection  machines.  Nine-tenths  of 
the  scratching  of  film  is  due  to  poorly  designed  projector 
take-up  tension  and  to  "pulling  down"  in  rewinding,  the 
latter  consisting  in  rewinding  a  portion  of  the  reel  loosely, 
then  holding  one  reel  stationary  while  revolving  the  other 
to  tighten  the  film  roll.  Injury  to  sprocket  holes  is,  in  the 
main,  chargeable  to  undercut  and  hooked  sprocket  teeth 
(see  General  Instruction  No.  8,  Page  462),  and  to  too  much 
pressure  by  the  tension  shoes  of  the  projector.  (See  General 
Instruction  No.  9,  Page  463.) 

Operators,  are,  I  believe,  as  a  rule,  reasonably  careful  in 
handling  film.  In  many  theatres,  however,  rewinding,  thread- 
ing the  machines  and  repairing  film  are  made  the  duty  of  an 
irresponsible  usher,  or  reel  boy,  and  what  he  does  to  the 
film  is  all  too  often  a  shame  to  tell.  Patches  half  and  even 
three-quarters  of  an  inch  wide;  patches  without  the  emulsion 
scraped  off,  and  patches  as  stiff  as  a  board  are  too  common 
to  excite  more  than  passing  comment,  and  film  spliced  to- 
gether with  pins  and  even  nails  are  often  sent  back  to  the 
exchange.  It  is  an  outrage,  but  one  which  cannot  always 
be  laid  at  the  door  of  the  operator.  Even  when  the  operator 
does  the  rewinding  and  patching,  he  is,  in  all  too  many  cases, 
expected  to  do  it  while  projecting  a  picture,  and  hence  must 
either  neglect  his  projection  or  his  rewinding  and  film  repairing. 
IN  THE  MAJORITY  OF  CASES  I  BELIEVE  THE  REAL 
UNDERLYING  FAULT  LIES  IN  THE  FAILURE  OF  THE 


FOR   MANAGERS    AND   OPERATORS  195 

THEATRE  MANAGER  TO  EMPLOY  SUFFICIENT  COM- 
PETENT HELP  IN  THE  OPERATING  ROOM.  FILM 
REPAIRING  SHOULD  NEVER,  UNDER  ANY  CIRCUM- 
STANCES, BE  LEFT  TO  USHERS,  BOYS,  OR  TO  ANY 
OTHER  THAN  THOROUGHLY  COMPETENT,  RESPON- 
SIBLE HELP. 

Injury  to  the  film  in  passing  through  the  modern  'motion 
picture  mechanism  is  invariably  due  to  either  the  bad  con- 
dition of  the  film  itself,  or  to  the  laziness,  carelessness  or 
lack  of  knowledge  of  the  operator,  or  to  the  false  economy 
of  managers  who  refuse  necessary  repairs  to  the  machine. 

THE  EXCHANGE  MANAGER  SEEMS,  IN  ALL  TOO  MANY  CASES,  NOT 
TO  REALIZE  THAT  SENDING  OUT  A  FILM  IN  BAD  CONDITION  IS  NOT 
ONLY  AN  OUTRAGE  AGAINST  THE  PRODUCER,  AGAINST  THE  OPERATOR 
WHO  MUST  RUN  IT,  AGAINST  THE  THEATRE  MANAGER  WHO  IS  PAY- 
ING FOR  FILMS  IN  GOOD  REPAIR  AND  AGAINST  THE  AUDIENCE  WHICH 
PAYS  MONEY  TO  SEE  AT  LEAST  A  REASONABLY  PERFECT  PERFORMANCE, 
BUT  IT  IS  A  DIRECT  INVITATION  TO  MORE  AND  GREATER  DAMAGE,  SINCE 
A  LOOSE  SPLICE  IS  LIKELY  TO  CATCH  ON  A  SPROCKET  IDLER  AND  SPLIT 
ANYWHERE  FROM  ONE  TO  THREE  OR  FOUR  FEET  OF  FILM  BEFORE  THE 
TROUBLE  IS  NOTICED,  ESPECIALLY  IN  HOUSES  WHERE  THE  OPERATOR 
IS  OBLIGED  TO  REWIND  AND  DO  OTHER  STUNTS  WHILE  HIS  MACHINES 

ARE  RUNNING.  Patches  in  which  sprocket  holes  are  not  properly 
matched  will  climb  the  sprocket  teeth,  causing  the  loss  of  a  loop, 
or  will  grip  the  teeth  of  the  sprocket  and  wrap  around  it.  Split 
sprocket  holes  will  catch  on  an  idler  and  a  section  of  the  edge 
of  the  film  will  be  split  off,  if  nothing  worse. 

Emulsion  deposits  on  tension  shoes  (See  General  Instruc- 
tion No.  10,  Page  464)  often  does  considerable  damage  to 
first  run  film. 

Mending  the  Film,  i.  e.,  making  patches  in  it,  is  a  matter 
which  is  of  the  utmost  importance.  Badly  made  patches  are 
the  cause  of  unending  annoyance,  as  well  as  immense  damage 
to  the  film  itself. 

If  the  patch  be  made, in  such  manner  that  the  sprocket 
holes  do  not  match  perfectly  there  is  likely  to  be  a  jump  of 
the  picture  on  the, screen  as  the  patch  goes  over  the  inter- 
mittent sprocket  teeth,  due  to  the  fact  that  the  hole  is  too 
small  to  allow  the  sprocket  tooth  seating  properly  therein. 
There  is  also  the  liability  of  (a)  the  hole  locking  on  the 
upper  sprocket  tooth  and, pulling  the  loop  around  under  the 
sprocket,  (b)  The  film  running  off  the  sprocket,  (c)  The 
intermittent  sprocket  climbing  one  or  more  holes,  thus 
shortening  one  of  the  loops,  making  the  other  proportion- 


196 


MOTION    PICTURE    HANDBOOK 


ately  longer  and  throwing  the  picture  out  of  frame,  (d)  The 
takeup  tension  pulling  the  film  over  the  lower  sprocket,  thus 
losing  the  lower  loop.  All  this  is  liable  to  occur  also  where 
one  of  the  holes  is  properly  matched,  but  the  other  is  not, 
thus  making  one  hole  small  and  making  the  film,  as  a  whole, 
crooked  at  that  point.  You  will  see,  therefore,  the  impor- 
tance o-f  matching  the  sprocket  holes  perfectly. 

In  the  operating  room  it  is  customary  to  make  patches  with 
the  fingers.  Film  cement  welds  more  than  it  glues  the  film 
together.  Considerable  pressure  is  therefore  necessary  to 
make  a  perfect  joint;  much  more  than  can  be  given  by  the 
fingers  alone.  Also  with  the  fingers  the  pressure  cannot  pos- 
sibly be  applied  evenly.  Until  recently  there  has  been  no 
film  mender  suitable  for  use  in  the  operating  room. 


ooo  ooo  o  ooooo  a 


Figure  75. 


To  Make  a  Patch  cut  the  film,  as  shown  in  Fig.  75,  leaving 
a  stub  as  shown  at  A.  This  stub  should  be  not  less  than 
one-eighth  inch  and  not  more  than  three-sixteenths  of  an 
inch  in  length.  The  latter  measurement  is  best,  as  it  will  be 
found  difficult  for  the  operator,  usually  working  in  a  hurry, 
to  make  a  good  patch  only  one-eighth  inch  wide;  but  if  wider 
than  three-sixteenths  the  patch  will  be  stiff.  End  B  should 
be  cut  exactly  on  the  dividing  line  between  two  pictures. 
Scrape  every  particle  of  emulsion  off  stub  end  A,  and  scrape 
about  one-eighth  inch  on  celluloid  side  of  end  B,  to  roughen 
the  celluloid  and  remove  all  dirt  and  grease.  A  very 
sharp  knife  is  best  to  scrape  with.  Some  use  the  blade 


FOR   MANAGERS    AND   OPERATORS  197 

of  a  safety  razor.  Be  sure  to  thoroughly  scrape  end  B  and 
to  scrape  every  particle  of  the  emulsion  off  stub  end,  A. 
Cement  will  not  stick  to  emulsion.  You  must  remember  that 
the  emulsion  covers  the  entire  film  on  one  side,  therefore  be 
careful  to  get  it  all  off  around  the  sprocket  holes.  This  is 
where  many  make  their  error  in  patching  film.  They  scrape 
the  center  of  the  stub  and  the  center  of  the  back  of  end  B, 
but  do  not  scrape  thoroughly  around  the  sprocket  holes, 
where  the  greatest  strain  will  come.  In  consequence  their 
patches  soon  come  loose  around  the  sprocket  holes  and  there 
is  trouble.  The  stub  should  be  scraped  to  a  straight  line,  as 
per  dotted  line,  else  there  will  be  a  flash  of  white  light  on 
the  screen  as  the  patch  passes.  It  matters  little  whether 
patches  be  made  as  per  C,  or  D,  Fig.  75.  Patches  made 
one  way  will  go  through  some  projectors  better  when  partly 
loose,  and  through  other  projectors  loose  patches  will  go 
through  if  made  the  other  way.  If  the  patch  is  in  good'  con- 
dition it  will  go  through  equally  well  either  way  it  is  made. 
Having  scraped  the  ends  clean,  as  directed,  place  them  to- 
gether so  that  the  sprocket  holes  exactly  match  (if  patch  is 
to  be  made  with  fingers),  with  the  emulsion  side  of  both 
ends  either  up  or  down — that  is  to  say,  on  the  same  side. 
Grasp  one  edge  firmly  with  thumb  and  finger  and  apply 
cement,  with  the  cement  bottle  brush,  to  the  other.  Clamp 
the  cement  edge  down  tightly,  being  careful  the  sprocket 
holes  exactly  match,  with  thumb  and  finger  of  other  hand 
releasing  opposite  edge.  Apply  cement  to  other  edge  and 
clamp  that  also,  applying  all  the  pressure  you  can  for  about 
ten  seconds  or  so,  and  the  patch  is  done.  Every  cement 
bottle  should  have  a  small  brush  attached  to  the  under  side 
of  its  cork.  When  you  buy  cement  accept  none  without  the 
brush.  It  is  put  up  that  way  now  by  many,  and  should 
be  by  all. 

Film  Cement  may  be  easily  made.  The  following  are  a  few 
formulas:  For  non-inflammable  stock,  one-half  pound  of 
acetic  ether,  one-quarter  pound  of  acetone  merch,  in  which 
dissolve  six  feet  of  non-inflammable  film  from  which  the 
emulsion  has  been  removed. 

For  inflammable  film,  a  piece  of  film  three  inches  long  dis- 
solved in  one  ounce  of  acetic  ether  is  a  satisfactory  cement, 
but  it  will  not  work  on  N.  I.  (non-inflammable)  stock.  In 
dissolving  the  film,  in  either  case,  first  remove  the  emulsion 
and  then  cut  the  film  into  fine  .strips. 


198  MOTION    PICTURE    HANDBOOK 

Acetone  Cement. — Four  ounces  of  acetone;  one-half  ounce 
ether;  six  inches  old  film,  from  which  remove  the  emulsion 
and  cut  into  strips. 

Another  Formula. — Equal  parts  of  amyl  acetate  and  ace- 
tone. Will  not  turn  white  on  film,  and  will  not  dissolve  the 
film  as  ether  will.  Works  on  all  kinds  of  stock.  Best  used 
with  an  all  steel  three  flap  film  mender.  Can  be  used  by 
those  making  patches  by  hand  if  worked  rapidly.  Scrape 
film,  use  small  camel  hair  brush;  keep  bottle  tightly  corked 
when  not  in  use. 

Still  Another. — One  ounce  collodion;  one  ounce  banana  oil 
or  bronzing  liquid;  one-half  ounce  ether.  For  Pathe  hand 
colored  films,  one-half  acetone  and  one-half  ether. 

N.  I.  Cement. — For  non-inflammable  film  add  one  part 
glacial  acetic  acid  to  four  parts  of  flexible  collodion  or  to 
any  of  the  film  cements.  It  is  satisfactory  for  either  N.  I. 
or  regular  film. 

Please  understand  that  these  are  formulas  sent  in  by  opera- 
tors from  time  to  time,  and  recommended  by  them.  The 
author  does  not  vouch  for  their  excellence. 

Size  of  Reels. — There  has  been  some  inclination  to  in- 
crease the  size  of  reels  to  two  and  even  three  thousand  feet, 
which  is,  I  think,  bad  practice.  With  two  projectors  there  is 
really  no  good  reason  why  it  should  be  done,  and  it  is  dis- 
tinctly objectionable  for  several  reasons,  one  of  which  is 
that  it  increases  the  probable  loss  should  a  fire  occur,  as 
well  as  increasing  the  volume  of  fire  and  smoke. 

One  thousand  feet  of  film  has  been  and  should  continue  to 
be  the  standard  reel  of  film.  It  is  convenient  to  handle,  not 
overly  heavy,  and  keeps  the  fire  damage  risk  within  reason- 
able limits.  But  the  reels  themselves  should  be  not  less  than 
12  inches  in  diameter.  Personally,  I  believe  a  14-inch  reel 
having  a  4-inch  hub  would  be  ideal  from  any  and  every  point 
of  view.  The  hubs  of  present  reels  are  too  small  Small  hubs 
and  the  old-style  takeup  tension  are  a  combination  which 
produce  heavy  strain  on  the  first  fifty  to  one  hundred  feet 
of  film.  But  whatever  is  done  in  that  direction,  the  reel  should 
be  of  sufficient  diameter  that  one  thousand  feet  of  the  thickest 
film  (yes,  film  stock  varies  slightly  in  thickness}  will  fill  it  to 
only  within  one-half  inch  of  its  outer  diameter,  assuming  the 
film  to  be  wound  not  too  tightly.  Thus  the  whole  film  will  be 
protected  by  the  metal  sides  of  the  reel. 


FOR   MANAGERS    AND   OPERATORS  199 

Overloading  reels  has  been  the  source  of  much  annoyance 
to  operators  in  the  past,  but  it  is  not  so! much  practiced  of 
late.  Apparently  even  the  exchanges  are  slowly  learning  to 
exercise  a  little  common  sense,  in  some  directions  at  least, 
in  the  care  of  their  property.  The  evil  of  the  overloaded 
reel  is  threefold:  (a)  That  portion  of  the  film  outside,  or 
above  the  sides  of  the  reels  is  absolutely  unprotected,  there- 
fore liable  to  injury  in  many <  ways;  also  it  is  likely  to  slip  off, 
to  the  exasperation  of  the  operator  and  possible  delay  of 
the  show  while  it  is  wound  on  'again,  to  say  nothing  of 
probable  damage  through  contact  with  the  more  or  less 
dusty,  dirty  floor,  (b)  The  increased  temptation  to  !"pull 
down,"  and  pull  down  good  and  hard,  too,  to  get  a^  much 
of  the  film  inside  the  reel  as  possible,  and  (c)  The  fact  that 
the  film  may  rub  against  the  magazine,  thus  scratching  the 
film,  and  possibly  interfering  with  the  operation  of  the 
takeup,  incidentally  requiring  a  very  tight  takeup  tension, 
which  is  bad  indeed,  and  a  prolific  source  of  damage  to  the 
first  part  of  the  film  through  scratching  and  pulling 'out  the 
lower  loop. 

Leader  and  Tail  Piece.— It  is  for  several  reasons  essential 
that  there  be  a  "leader"  and  an  opaque  tail-piece  on  every 
reel  of  film,  including  multiple-reel  features.  In  the  first 
place,  the  leader  protects  the  title  from  damage.  In  thread- 
ing into  the  takeup  it  is  frequently  desirable,  if  not  necessary, 
to  fold  an  inch  or  so  of  the  end  of  the  film  over  on  itself. 
By  so  doing  it  is  made  stiffer  and  is  more  easily  thrust  under 
the  reel-spring.  This  means  that  the  leader  will  occasionally 
break  where  it  is  folded;  hence  there  will  be  gradual  wasting 
av;ay.  If  this  occurs  on  the  title  the  damage  is  quite  evident. 
Soon  there  will  have  to  be  a  new  title  provided.  If,  however, 
it  is  only  a  leader  that  is  being  thus  damaged,  it  is  not 
serious.  But  there  is  another  reason  why  leaders  should  be 
used,  viz.,  in  rewinding,  when  the  job  is  done,  the  end  of  the 
film  often  flaps  around  anywhere  from  one  to  a  dozen 
times  before  the  reel  stops  revolving,  and  if  there  be  no 
leader  to  receive  the  brunt  of  this  rough  treatment,  the -title 
is  injured.  There  is  yet  another  reason  which  not  only  deals 
with  the  necessity  for  leaders,  but  also  with  their  length. 
About  30  inches  of  film  is  required  to  thread  into  the  takeup. 

If  there  be  not  enough  leader,  the  title  will  be  practically 
all  on  the  takenp  side  of  the  machine  aperture  when  threading 
is  completed.  In  order  that  the  run  may  commence  with  the 
first  image  of  the  title  it  is  necessary  that  there  be  not  less 
than  30  inches  of  leader.  If  the  title  be  short,  even  this  is 


200  MOTION    PICTURE    HANDBOOK 

not  sufficient.  -If  a  short  title  comes  on  the  instant  the 
machine  starts  it  will  be  gone  before  the  operator  can  frame 
up  and  adjust  his  light,  unless  the  film  be  threaded  in 
frame  on  the  first  title  picture,  or  the  leader  be  a  blank  which 
has  been  exposed  in  the  printing  machine  and  developed, 
thus  leaving  only  the  dividing  lines,  which  may  be  used  as  a 
guide  in  framing. 

As  a  matter  of  fact,  leaders  should  be  of  exposed  film, 
developed  very  dense,  ,and  at  least  full  four  feet  in  length. 
This  would  give  the  operator  time  to  frame  up,  adjust  his 
light  and  have  everything  just  right  when  the  title  comes 
on.  Under  these  conditions  if  the  machine  be  run  slowly  at 
the  start  the  title  would  have  to  be  very  short  indeed  if  the 
audience  could  not  read  it.  As  a  substitute  many  houses 
show  a  stereopticon  title  slide  before  running  the  reel.  I 
do  not  fancy  this  scheme.  It  savors  of  a  makeshift.  If 
things  are  as  they  should  be  there  will  be  no  necessity  for  a 
slide  title,  but  in  many  cases  it  is  unavoidable,  and  therefore 
better  than  nothing. 

"Ah  ha!"  I  think  I  .hear  some  of  you  say;  "you  condemn 
the  operator  who  does  not  thread  in  frame,  yet  now  advise 
the  use  of  leader  which  will  allow  of  framing  up  after  the 
machine  has  been  started." 

Right  you  are,  brother,  but  I  don't  make  conditions.  None 
but  Mr.  Sloppy  Workman  Operator  will  thread  his  machine 
out  of  frame,  and  frame  after  it  has  started,  but  unfortunately 
Mr.  S.  W.  Operator  is  still  a  numerous  tribe,  and  we  must 
therefore  take  that  fact  into  consideration  and  try  to  fix 
things  so  that  his  sloppyness  (a  crude  term,  I  grant  you — 
but  expressive}  will  do  the  least  possible  amount  of  harm. 

The  reason  for  also  advising  leader  and  tailpiece  on 
multiple-reel  features  lies  in  the  fact  that  they  will  only 
slightly  inconvenience  the  operator  in  the  two-machine  house, 
and  will  be  a  great  convenience  to  the  one-machine  house 
operator. 

I  strongly  advise  managers  to  insist  on  leaders  not  less 
than  48  inches  in  length  on  all  films;  also  that  they  be,  if 
possible,  of  the  kind  showing  dividing  lines.  If  exchanges 
will  not  supply  such  leaders  it  will  pay  theater  managers  to 
buy  blank  film  and  use  leaders  of  their  own. 

It  is  important  that  there  be  a  tailpiece  on  every  film.  It 
need  not  exceed  12  inches  in  length,  but  should  by  all 
means  be  there  and  should  be  of  the  opaque  variety.  When 
the  light  is  shut  off  by  the  tailpiece  the  machine  should  be 
instantly  stopped.  Many  operators  have  a  most  reprehensible 


FOR   MANAGERS   AND    OPERATORS  201 

habit  of  running  the  machine  until  the  end  of  the  film  has 
passed  over  the  aperture  and  the  white  light  is  on  the  screen. 
This  instantly  destroys  all  the  illusion.  It  is  in  the  nature 
of  a  most  unpleasant  shock,  particularly  if  the  audience  be 
deeply  interested  in  the  picture. 

Stop  your'  machine  while  the  tailpiece  is.  over  the  aperture. 
If  there  be  no  tailpiece,  stop  the  machine  -when  the  end  of  the 
film  comes  out  of  the  upper  magazine,  before  it  has  got  past 
the  aperture.  Never,  under  any  circumstances,  allow  white  light 
to  show  on  the  screen.  SUCH  WORK  is  CRUDE  IN  THE  EXTREME. 

Inspection. — The  operator  should,  so  far  as  possible,  re- 
pair all  the  damage  he  himself  inflicts  upon  a  film  while  it 
is  in  his  possession. 

However,  it  is  the  duty  of  the  film  exchange  thoroughly  to 
inspect  all  films  as  they  are  received  from  theatres,  and  put 
them  in  A\  condition  before  they  are  again  sent  out. 

WHERE  FILMS  ARE  USED  IN  CIRCUIT  IT  SHOULD  BE  A  POINT  OF 
HONOR  WITH  EACH  OPERATOR  TO  SEND  THE  FILMS  AWAY  IN  AS  GOOD 
CONDITION  AS  THEY  'WERE  RECEIVED.  DON'T  leave  it  to  your 
brother  operator  who  gets  them  next,  to  repair  the  damage  you 
do.  You  are  in  position  to  "pass  the  buck,"  true,  but  IT  is  NOT 

A  VERY  MANLY  THING  TO  DO. 

Perfect  projection  is  impossible  where  a  film  is  in  imper- 
fect condition,  and  a  film  is  not  in  perfect  condition  when  it 
has  wide,  stiff,  or  loose  patches,  misframes,  ripped  sprocket 
holes,  etc.  These  faults  are  prolific  sources  of  imperfection 
in  projection. 

It  is  a  well  known  fact  that  many  film  exchanges  make  but 
the  most  superficial  inspection  of  film  and  all  too  frequently 
no  repairs  at  all.  The  underlying  cause  of  poor  inspection 
and  repair  of  films  is,  I  believe,  the  endeavor  on  the  part 
of  exchanges  to  get  too  much  work  out  of  a  film,  as  well 
as  an  unwillingness  to  expend  the  proper  amount  of  money 
in  the  employment  of  enough  and  competent  inspectors.  In 
many  exchanges  men  or  girl  inspectors  are  employed,  at  low 
wages,  and  are  expected  to  "inspect"  anywhere  from  fifty 
to  seventy-five  reels  of  film  a  day,  which  is  from  two  to  five 
times  (dependent  on  condition)  as  many  as  they  can  inspect 
and  repair  properly. 

In  such  exchanges  the  inspection  very  largely  consists  in 
running  a  film  from  one  reel  to  another  at  top  speed.  The 
only  faults  ordinarily  detected  by  this  sort  of  performance 
are  the  very  bad  ones,  such  as  long  strings  of  ripped 
sprocket  holes,  a  patch  loose  half  way  across  the  film,  or  the 
film  torn  entirely  in  two.  MINOR  FAULTS  CANNOT  POSSIBLY  BE 


202  MOTION    PICTURE    HANDBOOK 

DETECTED    BY    ANY    SUCH    WHIRLWIND    INSPECTION.       It    is    a    known 

fact,  and  a  most  reprehensible  practice,  too,  that  exchange 
managers  will  often  ship  reels  out  to  exhibitors  without  any 
inspection  at  all.  This  practice  is  often  aggravated  by  the 
exhibitor,  who,  when  in  a  hurry  for  reels,  demands  that  they 
be  given  him  without  waiting  for  any  inspection  at  all.  It  is 
also  a  fact  that  exhibitors  who  do  this  will  frequently  upbraid 
the  exchange  if  the  films  are  in  bad  condition,  and  will  blame 
the  operator  if  breaks  occur  and  the  show  is  stopped.  When 
a  film  leaves  the  exchange  in  anything  but  the  best  possible 
condition  a  wrong  is  done  to  everybody  concerned,  from 
the  producer  to  the  theatre  audience.  The  result  of  faulty 
exchange  inspection  is,  so  far  as  the  operator  be  concerned, 
one  of  two  things:  either  it  falls  to  him  to  do  a  lot  of  work 
which  is  no  part  of  his  duty  and  for  which  he  is  not  paid, 
inspecting  the  films  and  putting  them  into  condition,  or,  as 
an  alternative,  the  projection,  and  incidentally  his  reputation 
as  an  operator  will  suffer. 

I  am  well  aware  that  the  question  of  inspection  and  repair 
presents  a  problem  of  many  angles,  and  one  not  at  all  easy 
to  adjust.  However,  this  I  can  say  without  fear  of  successful 
contradiction:  there  is  absolutely  no  excuse  whatsoever  for 
the  utterly  miserable  condition  in  which  many  films  are 
received  by  the  operator. 

/  am  heartily  in  favor  of  operators  demanding  overtime  for 
inspecting  and  repairing  film  when  they  are  received  in  bad 
condition.  It  most  emphatically  is  NOT  a  part  of  their  duty, 
and  by  what  process  of  reasoning  a  theatre  manager  justifies 
his  demand  that  his  operator,  without  any  remuneration  what- 
ever, do  the  work  of  an  exchange  inspector,  I  have  never  been 
able  to  understand. 

There  is  now  on  the  market  a  film-fault  detector,  the  in- 
vention of  one  Rosenfeld,  through  which  a  film  may  be  run 
at  tolerably  high  speed,  and  which  will  automatically  detect 
all  loose,  wide  or  stiff  patches,  mis-frames,  and  other  mechan- 
ical defects.  This  machine  also  has  an  appliance  for  making 
a  patch,  which  joins  the  film  properly,  and  insures  a  splice 
of  uniform  width  from  which  the  emulsion  has  been  entirely 
scraped.  It  also  at  the  same  time  cleans  the  film  by  passing 
it  through  a  bath  of  chemicals  and  washing  it  with  brushes. 
With  such  a  device  in  existence  there  is  no  longer  any  ex- 
cuse whatever  for  the  mechanical  faults  found,  in  greater 
or  less  amount,  in  nine  out  of  ten  films  sent  out  by  the 
average  exchange. 

There  is  now  on  the  market  a  neat  little  cutting  plier  with 
which  broken  sprocket  holes  may  be  notched  as  per  Fig.  76. 


FOR    MANAGERS   AND    OPERATORS  203 

This  is   a  tool   which  should!  be  in  the  hands  of  every  ex- 
change  inspector   and   operator.      It   is   the   invention   of  A. 


»  -irww9  •  •    ^s  i  •  i 


Figure  76. 

Jay  Smith,  Cleveland.    The  price  is  $2  and  well  worth  it. 

Where  to  Keep  Films. — Film  should  be  kept  near  the  floor 
of  the  operating  room,  since  near  the  ceiling  it  is  much 
warmer.  It  should  be  kept  in  a  metal  box  having  compart- 
ments for  each  reel,  and  one  compartment  below  to  hold  a 
wet  sponge  ©r  water.  The  film  should  be  treated  with  a  little 
glycerine  once  in  a  while,  but  this  is  only  accomplished  by 
having  the  film  in  actual  contact  with  the  liquid,  as  per 
directions  further  on.  The  glycerine  is  for  the  purpose  of 
keeping  the  film  soft  and  pliable,  which  it  does  by  reason  of 
the  fact  that  it  has  the  property  of  rapidly  absorbing  mois- 
ture. 

Should  water,  by  any  accident,  be  spilled  over  a  reel  of 
film,  or  it  even  be  dropped  in  a  pail  of  water,  it  may  be  saved 
from  damage  if  unrolled  very  quickly,  not  allowing  the 
emulsion,  which  will  be  quickly  softened,  to  touch  anything. 
But  the  unrolling  must  be  done  very  quickly  or  the  emul- 
sion will  stick  to  the  back  of  the  film  and  pull  off.  This  does' 
not  apply  to  colored  or  tinted  film,  though  even  these  may 
sometimes  be  saved  by  very  prompt  action.  The  writer  once 
rescued  a  first-run  film  from  destruction  thus:  He  happened 
to  be  in  the  operating  room  after  the  show  had  closed  for 
the  night.  In  taking  the  last  reel  from  the  magazine  it 
slipped  from  the  operator's  hands  and  landed  in  a  pail  of 
water,  being  practically  submerged.  He  grabbed  the  reel, 
ran  down  stairs,  handed  the  end  to  an  usher,  ran  to  the  front 
end  of  the  theatre,  looped  the  film  over  a  chairback,  and 
ran  back  and  forth  until  the  whole  film  lay  across  the  back 


204  MOTION    PICTURE    HANDBOOK 

of  the  seats.  The  emulsion  became  very  soft  in  places,  but 
next  morning  it  was  found  that  a  total  of  less  than  five  feet 
was  damaged.  The  exchange  men  never  knew  of  the 
occurrence  until  more  than  a  month  after,  when  they  were 
told  of  it. 

Moistening  Dry  Film. — Traveling  exhibitors  often  find  that 
a  reel  which  has  been  a  long  time  in  use  has  become  very  dry 
and  brittle.  It  may  be  remoistened  and  rendered  pliable  by 
unwinding  into  a  large  metal  can,  in  the  bottom  of  w'hich 
water  has  been  placed,  with  a  wire  screen  over  it  to  keep  the 
film  from  contact  therewith.  Cover  tightly,  set  in  a  mod- 
erately warm  place  until  the  film  is  soft  and  pliable.  Watch 
closely,  however,  since  if  made  too  moist  the  emulsion  will 
stick  to  the  back  of  the  film  when  it  is  rewound. 

It  is  even  possible  to  give  a  film  a  glycerine  bath,  as  fol- 
lows: In  a  long,  shallow  pan  place  a  solution  of  30  parts  of 
clear  water  to  one  part  of  glycerine.  Make  a  drum  of  slats 
about  six  feet  in  diameter  by  about  six  feet  long  (for  one 
thousand  feet  of  film),  and  by  revolving  the  drum  draw  the 
film  very  slowly  through  the  liquid,  winding  on  the  drum  with 
the  emulsion  side  out.  After  the  film  is  all  on  the  drum, 
revolve  it  rapidly  to  throw  off  the  surplus  liquid,  then  con- 
tinue to  revolve  the  drum  slowly  until  the  film  is  dry.  It 
should  not  be  used  for  two  or  three  days.  Perform  this 
operation  in  a  room  entirely  free  from  dust,  or  you  may 
seriously  injure  your  film. 

Due  to  lack  of  proper  inspection  it  is  usually  advisable, 
where  practical,  to  inspect  the  films  at  the  theater  before 
they  are  run.  To  do  this  place  the  reel  on  rewinder,.  and  re- 
wind it  very  slowly,  holding  the  edges  between  the  thumb 
and  forefinger  with  pressure  enough  to  cup  it  slightly.  By  so 
doing  you  instantly  detect  all  stiff  or  loose  patches.  Cut  out 
the  stiff  ones  and  remake.  Cement  all  loose  patches  and 
notch  all  split  sprocket  holes.  If  more  than  two  sprocket 
holes  are  missing  on  one  side — that  is,  in  succession,  of 
course — cut  the  film  and  make  a  patch.  Inspection  pays,  and 
an  ounce  of  prevention  is  worth  a  pound  of  cure.  Managers, 
however,  should  not  expect  operators  to  inspect  films  for 
nothing.  Such  work  is  no  part  of  an  operator's  duty  and 
should  by  all  means  be  paid  for,  aside  from  the  operator's 
regular  salary. 

Stretched  Film. — Ignorance,  poor  judgment,  or  carelessness 
in  the  drying  room  or  the  use  of  wrongly  designed  drying 
racks  or  drums  is  also  responsible  for  much  trouble.  Film 


FOR   MANAGERS   AND    OPERATORS  205 

which  is  wound  tightly  on  an  unyielding  drying  rack  or  drum 
will  in  all  probability  be  badly  stretched,  and  in  consequence 
the  picture  on  the  screen  will  be  unsteady.  This  fault 
usually  may  be  detected  by  doubling  two  or  three  feet  of  the 
film  back  on  itself,  matching  two  sprocket  holes  and  then 
seeing  if  the  rest  match.  Stretched  film  will  not  fit  the  projector 
sprockets  properly,  hence  will  not  produce  a  steady  piciure  on 
the  screen. 

Operators  using  first-run  film  will  often  notice  a  tendency 
of  the  film  to  curl  up,  or  "cup"  edgewise,  with  a  flat  spot 
every  few  inches  when  the  film  is  unrolled  loosely.  This 
is  evidence  that  it  has  been  dried  on  a  drum  covered  with 
slats  spaced  as  far  apart  as  the  flat  spots  occur.  Such  film 
will  have  a  tendency  to  buckle  more  or  less  over  the  aperture 
plate,  producing  an  in-and-out-of-focus  effect  on  the  screen. 
The  buckling  may  or  may  not  be  sufficient  to  be  readily  de- 
tected in  the  picture,  but  it  is  pretty  sure  to  be  present  in 
some  degree  where  such  film  is  used,  and  even<  though  you 
cannot  detect  a  distinct  change  in  the  definition  of  the 
picture  (the  flat  spots  are  usually  not  more  than  6  inches 
apart,  therefore  the  effect  is  too  nearly  continuous  to  be 
readily  detected  by  the  eye  as  a  separate  phenomena  every 
time  a  flat  spot  goes  through)  each  time  a  flat  spot  passes 
the  aperture,  the  effect  is  there  and  manifests  itself  by  an 
injury  to  the  sharpness  of  the  picture.  See  "effect  of  loss  of 
definition,"  Page  152.  From  what  I  have  learned  from  some 
of  the  oldest  drying-room  men  in  the  business,  film  should 
not  be  dried  on  a  drying  frame,  but  be  wound  on  a  large 
drum,  having  round-face  slats  not  to  exceed  one-half  inch 
wide,  spaced  not  more  than  two  inches  center  to  center, 
or,  better  yet,  though  the  process  of  drying  would  be  slower, 
the  face  of  the  drum  covered  solid.  In  either  case  the  drum 
should  be  so  made  that  as  the  film  shrinks  in  drying  the 
diameter  of  the  drum  will  be  decreased  against  the  pressure 
of  springs. 

I  am  not  a  film  producer  or  drying-room  man,  but  the 
foregoing  seems  to  be  based  in  common  sense.  It  appears 
reasonable  on  the  face  of  it.  There  is  no  manner  of  question 
but  that  film  is  often  stretched  in  drying,  and  that  f.he 
alternate  cupping  and  flat  spots  are  often  present.  Also  there 
is  no  manner  of  doubt  but  that  these  things  cause  more  or 
less  trouble  w>hen  the  film  is  projected.  If  the  producer 
disputes  the  correctness  of  what  is  herein  set  forth,  let  bim 
set  forth  better  reasons  for  the  stretching  and  the  cupping 


206  MOTION    PICTURE    HANDBOOK 

and  flat  spots,  and  then,  since  he  will  be  convicted  of  knowl- 
edge of  the  cause,  let  him  produce  and  apply  the  remedy. 

Emulsion  May  Be  Removed  from  Film  by  soaking  the  film 
in  warm  water,  to  which  ordinary  washing  soda  'has  been 
added.  Put  in  large  double  handfull  of  soda  to  the  bucket 
of  water.  Wash  the  film  afterward  in  clean,  warm  water. 

CLEANING  FILM 

Cleaning  film  is  an  exceedingly  important  item  in  projec- 
tion. The  rain  marks  you  see  are  nothing  more  or  less 
than  slight  scratches  in  the  emulsion,  which  may  or  may 
not  have  removed  that  part  of  the  silver  carrying  the  image, 
but  which  have  filled  up  with  dirt,  thus  becoming  either 
opaque  or  semi-opaque.  With  this  dirt  removed  these 

scratches  would  for 
the  most  part  be  in- 
visible, or  nearly  so. 
I  have  seen  a  piece  of 
film  which  was  in  lit- 
erally terrible  condi- 
tion with  reference  to 
rain  marks  projected 
after  a  thorough  clean- 
ing, and  it  was  almost 
__  like  a  first  run. 

Cleaning    films    with 

liquids,  however,  is  not  a  thing  to  be  undertaken  without  proper 
knowledge.  Alcohol  will  remove  the  dirt,  and  will  not  injure 
the  emulsion,  but  it  is  likely  to  cause  the  film  to  curl  very 
badly,  therefore  it  is  not  to  be  recommended  for  film  cleaning. 
There  .are  now  on  the  market  two  film  cleaning  fluids 
which  have  the  approval  and  indorsement  of  the  Projection 
Department  of  the  Moving  Picture  World.  These  fluids  have 
been  thoroughly  tested  by  the  department  editor.  The  film 
can  be  washed  in  these  chemicals  without  injury.  They  do 
not  cause  the  film  to  curl,  and  do  in  every  way  a  satisfactory 
job.  One  of  these  cleaners  is  made  by  the  Githcil  Com- 
pany, New  York  City,  and  the  other  by  the  William  Rhodes 
Film  Company,  Hartford,  Conn. 

A  less  thorough  method  of  film  cleaning,  but  one  more 
readily  applicable,  is  found  in  the  Mortimer  Film  Cleaner, 
illustrated  in  Fig.  77.  This  cleaner  is  designed  to  be  fast- 
ened to  the  rewinding  table  between  the  reels.  It  opens  on 


FOR  MANAGERS  AND  OPERATORS 


207 


a  hinge,  and  the  film  is  drawn  between  two  felt  pads.  This 
cleaner  serves  more  than  one  purpose.  It  removes  a  con.- 
siderable  quantity  of  dust  and  oil,  and  by  so  doing  improves 
the  projection.  It  also  detects  loose  patches  and  as  a  rule 
pulls  them  in  two,  which  is  much  better  than  having  them 
pulled  in  two  in  the  projector,  thus  stopping  the  show.  If 
this  little  cleaner  were  used  continuously  in  all  theatres  it 
would  do  much  to  improve  results  on  the  screen,  but  in 
order  to  get  the  greatest  amount  of  benefit  from  a  device  of 
this  kind  the  film  must  be  subjected  to  the  process  contin- 
uously; that  is  to  say,  at  each  rewinding.  Results  would  also 
be  improved  if  one  of  the  clean- 
ing fluids  named  were  used  in 
conjunction  with  the  Mortimer 
Cleaner. 

Another  excellent  device  for 
cleaning  film  is  the  Ideal  Film. 
Cleaner,  shown  in  Fig.  78. 
This  device  consists  of  base 
casting  D,  carrying  arm  A  upon 
which  are  mounted  spools  B-B. 
Upon  each  of  these  spools  is 
wound  a  strip  of  cotton  flannel 
9  feet  long. 

The  way  the  film  passes 
through  the  machine  is  very 
clearly  shown.  Arm  A  is  car- 
ried at  its  lower  end  by  a  spin- 
dle attached  to  the  upper  end 
of  base  casting  D,  and  is  held 
in  upright  position  by  a  coil  Figure  78. 

spring,  so  that  when  the  re- 
winder  is  started  with  a  sudden  jerk  or  from  any  other 
cause  the  tension  becomes  too  great  the  upper  spool  is  pulled 
down  slightly  against  the  pressure  of  the  spring,  thus  lessen- 
ing the  tension  on  the  film.  Under  screws  C-C  is  a  coil 
spring  which  holds  spools  B-B  over  against  arm  A.  In  the 
caps  of  the  other  end  of  spools  B-B  are  six  holes  similar  to 
those  seen  in  front  caps,  and  one  of  these  holes  engages 
with  a  dowel  pin  in  arm  A.  When  a  section  of  the  cloth 
becomes  soiled  all  that  is  necessary  to  bring  a  new  strip 
into  place  is  to  pull  outward  on  either  one  of  the  spools 
against  the  pressure  of  the  coil  spring,  which  releases  the 
spool  from  the  dowel  pin,  whereupon  you  can  revolve  it  and 


208  MOTION    PICTURE    HANDBOOK 

bring  a  new  surface  of  cloth  against  the  film,  snipping  off 
the  soiled  piece  with  a  pair  of  shears. 

'  I  think  the  action  of  the  device  is  made  clear  by  this 
explanation  and  the  photograp'h.  Both  the  Ideal  .and  Morti- 
mer have  the  approval  of  the  Projection  Department  of  the 
Moving  Picture  World,  and  one  of  these  devices  ought  to  be  in 
every  operating  room,  since  it  will  be  worth  its  price  merely 
for  the  removing  of  oil  from  the  film. 

CLEANING  MACHINE  AFTER  FILM   FIRE 

Burning  film  leaves  a  sticky,  brown  colored  gummy  sedi- 
ment on  metal.  This  may  be  instantly  removed  by  washing 
with  ordinary  peroxide  of  hydrogen,  which  may  be  had  in  25 
cent  bottles  at  any  drug  store. 

THE  LIFE  OF  FILM 

There  have  been  many  inquiries  with  regard  to  the  "life 
of  film,"  that  is  to  say,  those  interested  have  wanted  to  know 
the  length  of  time  a  negative  or  positive  print  could  be  pre- 
served in  usable  form.  The  only  authentic  information  I 
have  been  able  to  obtain  is  contained  in  the  following  ex- 
cerpts from  letters  received  from  the  Eastman  Kodak  Com- 
pany, the  Vitagraph  Company,  and  the  Lubin  Manufacturing 
Company.  The  Eastman  Kodak  Company  says: 

"We  cannot  give  you  information  which  could  be  considered 
as  absolutely  authentic,  but  from  the  experience  we  have  had  we 
believe  it  is  possible  to  keep  processed  film,  both  negative  and 
positive,  with  but  slight  fear  of  deterioration,  provided  the 
proper  amount  of  precaution  be  used.  In  the  the  first  place 
it  is  absolutely  imperative  that  all  traces  of  the  hypo  be  removed 
in  the  developing  process  before  the  film  is  dried;  secondly, 
there  should  be  no  contact  with  any  metal  in  any  way,  either 
by  being  wound  on  a  metal  reel  or  stored  in  the  usual  tin 
containers.  The  film  should  be  tightly  wound  and  then 
wrapped  in  tissue  paper,  with  an  additional  oil  tissue  outer 
wrapping,  and  then  placed  in  a  wooden  box,  which  in  turn 
may  be  stored  in  a  vault  or  safe,  or  placed  where  the  atmo- 
sphere is  of  normal  temperature  and  humidity.  It  might  be 
well  in  winding  the  film  to  see  that  no  unusual  amount  of 
moisture  is  wound  into  it.  This  small  amount  of  informa- 
tion is  about  all  we  have  on  the  subject,  but  if  the  foregoing 
be  carefully  carried  out  there  is  every  reason  to  believe  that 


FOR    MANAGERS   AND    OPERATORS  209 

the  film  will  remain  in  a  state  of  excellent  preservation  for 
years." 

Mr.  J.  Stuart  Blackton  of  the  Vitagraph  Company  says: 
"On  the  fourth  of  July  four  years  ago  our  New  York  office 
was  burned,  and  all  the  old  films  we  had  been  keeping  in  a 
large  iron  safe,  in  hermetically  sealed  boxes,  were  destroyed. 
It  is  my  opinion,  however,  that  films  of  the  present  make, 
if  sealed  up  in  air  tight  boxes,  would  keep  for  a  very  long 
time.  However,  all  the  films  over  ten  years  old  that  I  have 
seen  and  tried  to  run  on  a  machine  were  very  brittle  and  in 
such  bad  shape  that  it  was  almost  impossible  to  keep  the 
picture  on  the  screen,  this  being  due,  no  doubt,  to  the  fact 
that  they  had  not  been  kept  from  contact  with  the  atmo- 
sphere." 

Mr.  Siegmund  Lubin,  president  of  the  Lubin  Manufac- 
turing Company,  says:  "So  far  as  the  writer  knows,  a  nega- 
tive will  keep  indefinitely;  that  is  to  say,  the  way  we  keep 
negatives,  viz:  by  winding  them  in  small  rolls,  placed  in 
small  cans  having  lids.  We  have  found  negatives  which  we 
have  had  sixteen,  seventeen  and  eighteen  years  to  be  in 
practically  the  same  condition  now  as  when  they  were  taken, 
with  a  possible  exception  that  they  might  be  a  trifle  darker, 
though  not  enough  to  affect  the  negatives  seriously." 

This  seems  to  be,  up  to  date,  the  only  available  informa- 
tion. It  comes  from  gentlemen  who  are  perhaps  best  com- 
petent of  judging,  but  even  they  are  uncertain  as  to  the 
exact  facts,  only  one  advocating  hermetically  sealing 

I  would  presume  that  the  advice  of  the  Eastman  Kodak 
Company  with  reference  to  the  method  of  packing  would  be 
best.  They  are  in  the  film  manufacturing  business,  and  may 
be  presumed  to  have  superior  knowledge  of  the  best  method 
of  treating  their  own  product.  I  might  add  to  this  by  say- 
ing that  I  have  myself  seen  film  which  was  fully  ten  years 
old,  and  which  had  received  no  particular  special  treatment, 
yet  seemed  to  be1  as  pliable  and  in  as  good  condition  as  the 
day  it  was  made. 

Summing  up  the  whole  matter,  my  own  belief  is  that  at 
or  near  sea  level,  where  the  atmosphere  contains  the  ordinary 
amount  of  humidity,  films  packed  according  to  the  sugges- 
tion of  the  Eastman  Kodak  Company  would  keep  in  prac- 
tically perfect  condition  for  at  least  fifteen  years  ;  beyond  that 
it  would  be  merely  a  matter  of  speculation.  However,  the 
caution  with  regard  to  thorough  washing  out  of  the  hypo  is 
highly  important.  The  ±east  trace  of  hypo  would,  in  the 
course  of  years,  cause  stains  which  would  ruin  the  picture. 


210  MOTION    PICTURE    HANDBOOK 

MEASURING  FILM 

The  Edison,  Power,  Simplex,  Motiograph,  Standard  and 
Baird  projection  machines  all  pass  exactly  one  foot  of  film 
to  each  turn  of  the  crank,  so  that  the  number  of  feet  in  a 
reel  may  be  measured  by  running  it  through  one  of  these 
machines  and  counting  the  number  of  turns  of  the  crank, 
which  will  equal  the  number  of  feet  in  a  reel. 


Figure  79. 

In  Fig.  79  a  film-measuring  machine  is  shown;  the  pic- 
ture is  self  explanatory.  This  particular  machine  is  made  by 
the  Nicholas  Power  Company.  Several  American  makes  of 
film  measurers  are  on  the  market  as  well  as  instruments  of 
English  and  French  manufacture. 

A  very  good  film  measurer  may  be  made  by  disconnecting 
the  intermittent  of  a  standard  projector,  using  only  the  upper 
sprocket — one  turn  of  the  crank,  one  foot  of  film. 

The  Operating  Room 

MORE  and  more  the  moving  picture  theatre  owners  and 
managers    are    coming    to    recognize    the    proposition 
that  not  only  is  it  necessary  to  good  results  that  the 
operating  room  be  equipped  with  up-to-date  appliances,  but 
also  that  the  room  itself  be  commodious,  carefully  constructed, 


FOR   MANAGERS    AND   OPERATORS  211 

and  supplied  with  running  water,  as  well  as  with  thorough 
ventilation.  The  following  may  be  taken  as  the  essentials 
of  a  first  class,  up-to-date  operating  room: 

1.  It  should  be  located  central,  sidewise,  with   regard   to 
the  screen,  and  as  nearly  as  possible  so  that  its  floor  will  be 
3   feet  below  the  level  of  the  center  of  the   screen,   though  a 
considerable   pitch  in  projection  will  not  seriously  mar  the 
effect. 

2.  It  should  not  be  placed  nearer  to  the  screen  than  50 
feet,  and  may  be  placed  as  far  away  as  250,  or  even  300  feet, 
though   125   should  be  the  maximum,   since   above   that   dis- 
tance it  becomes  difficult  to  match  up  the  optical  system  of 
the  projector  so  as  to  give  the  best  possible  results  for  the 
power  consumed. 

3.  It  should  be  absolutely  fire-proof  in  every  respect,  hol- 
low tile,  concrete  or  brick  being  the  best  materials  for  the 
construction    of    the    walls    and    ceiling,    and    concrete    with 
cement  finish  best  for  the  floor.     Asbestos  millboard  on  a 
substantial   angle-iron   frame  makes   a   fairly  good   room,   if 
properly  constructed,  though  it  does  not  compare  at  all  favor- 
ably with  concrete,  brick  or  hollow  tile.     One  objection  to 
this  form  of  construction  is  that  it  is  very   far  from  being 
sound-proof,   so   that   a   noisy   economizer   or   projector,   re- 
winder,  or  even  talking  in  the  operating  room  is  apt  to  be 
annoying  to  the  audience.     Rooms  of  this  kind  should  have 
double  walls  and  ceiling,  separated  by  an  air  space.     When 
the   walls   are  of   concrete   or  hollow   tile   I   would   strongly 
recommend  that  the  ceiling  be  of  the  same  material. 

4.  It  must  have  a  solid  foundation,  since  the  least  vibra- 
tion  in   the   floor   will  inevitably   affect   the   picture    on   the 
screen.    You  absolutely  cannot  have  a  shaky  operating  room 
floor  and  a  steady  picture  on  the  screen. 

5.  It  should  be  as  nearly  as  possible  sound-proof,  to  the 
end  that  the  noise  of  the  machines,  rewinding,  or  anything 
else  that  goes  on  in  the  operating  room  will  not  annoy  the 
audience.     This  is  of  much  importance. 

6.  It  should  be  provided  with  sufficient  incandescent  lights, 
arranged  to  instantly  and  brilliantly  illuminate  all  parts  of  the 
room;    also   there   should  be  an   extension   cord,   with   a  lamp, 
provided  with  a  guard,  which  may  be  carried  to  any  point 
in  the  room. 

7.  It  should  be  reasonably  easy  of  access,  preferably  not 
opening  directly  into  the  auditorium,  and  should  be  reached 
by  a  stairway,  rather  than  by  a  ladder.     If  it  opens  directly 


212  MOTION    PICTURE    HANDBOOK 

into  the  auditorium,  then  the  stairway  or  ladder  should  be 
surrounded  by  some  sort  of  partition,  so  that  in  case  of  fire 
the  operator  can  leave  the  room  without  letting  a  cloud  of 
smoke  into  the  auditorium  to  terrify  the  audience. 

8.  It  should  be  large  enough  to  hold  all  apparatus  and  still 
allow  not  less   than  two  feet   (three   is   better)   in  the  clear 
behind   the   machines   after   they    have   been    set   far   enough 
back  from  the  front  wall  so  that  the  operator  can  pass  be- 
tween  the   lens   and  the  wall,  with  not  less  than  6  feet   in 
width  for  a  single  machine  and  three  additional  feet  for  each 
additional  projector,  stereopticon  or  spot  light.     The  ceiling 
should  be  as  high  as  possible — the  higher  the  better,  within 
reason,  of  course,  but  should  in  no  case  be  less  than  six  and 
one-half  feet  in  the  clear.     That  should   be   regarded  as  an 
absolute  minimum,  but  less  than  seven   is  very  bad. 

9.  All   openings  should  be   equipped  with  fire-proof  shut- 
ters  which   will   close   quickly   and    automatically  in   case  of 
fire,  except  the  vent  flue,  which  must  be  unobstructed  if  there 
is  a  fan,  and  if  of  the  open  type  must  have  a  damper  weighted 
to   remain  normally   open,   as  will   be   hereinafter   explained. 
The  observation  port  should  be  fitted  with  a  movable  shutter 
which  can  be   raised  or  lowered  to   suit  the   convenience  of 
the  operator,  as  will  be  set  forth  further  along. 

10.  There  should  be  a  vent  flue  leading  as  nearly  as  pos- 
sible   directly    to   the    open    air    above    the    roof.      If    of   the 
open  type  this  flue  should  have  an  area  of  at  least  288  square 
inches,  regardless  of  the  number  of  projectors  used   or  the 
size  of  the  room.     There  will  be  just  as  much  smoke  from 
a  film  burning  in  a   small  room   as  from   one  burning  in   a 
large   room.     If  a   fan   is   installed  in   the   vent   flue  then   it 
should  be  large  enough  to  accommodate  a  16-inch  fan.    There 
should   be    a    separate    vent   flue   in    the    rewinding   room,    if 
there  be  one,  of  the  same  dimensions  as  the  one  in  the  main 
room. 

11.  The  interior  walls  and  ceiling  should  be  painted  with 
a   very   dark    or   black   flat   paint — paint   without    any   gloss. 
This  is  important   because   of  the   fact  that  the   darker  the 
operating  room  the  better  able  will  the  operator  be  to  see  the 
shadows  in  his  picture. 

12.  All  wires  should  be  in  conduit,  and 'the  conduit  system 
thoroughly  grounded.    Fuses  and  switches  should  be  in  metal 
cabinets,  or  in  cabinets  built  into  the  wall  and  covered  with  a 
metal    facing.      Conduits    should,    where    possible,    be    built    in 
the  walls,   and  conduits  leading  to  the  projectors  should  be 


FOR    MANAGERS   AND    OPERATORS  213 

carried   under    the    floor   to   a   point    immediately    under    the 
lamphouse  of  each  projector. 

13.  Iron  lined  operating  rooms  should  not  be  allowed,  but 
if  they  are,   then  the   floor   should   be  covered   with   a   good 
insulating  floor  covering,  such  as  cork  matting,  rubber  mat- 
ting, or  heavy  linoleum. 

14.  The    room   should    contain    nothing   except   the   things 
necessary  to  the  work  of  projection. 

15.  There  should  be  proper  tool  racks  and  closets  for  each 
operator's   clothes  and  tools,  a  substantial   work  bench  with 
a  good  vise,  though  this  need  not  necessarily  be  located  in 
the  operating  room. 

16.  The  arrangements  should  be  such   that  all  apparatus, 
switches,  etc.,   will  be  easy  of  access   to  the  operator,   both 
for  manipulation  and  repair.     It  never  pays  to  make  things 
unhandy.     On   the  contrary   it   does   always   pay   to   arrange 
them  conveniently. 

17.  It  should  contain  only  the  most  up-to-date  apparatus, 
and    that    apparatus    should    be    kept    in    perfect    condition. 
It  should   (and  this  is  of  paramount  importance — it  cannot  be 
too  strongly  emphasised}  have  observation  ports  of  amply  large 
proportions  so  that  the  operator  may  have  a  clear,  unobstructed 
view  of  the  entire  screen,  either  when  seated  or  standing  in  oper- 
ating position.     This  may  be  readily  accomplished  by  installing 
a  special  sliding  port  shutter,  as  will  be  hereinafter  explained. 

18.  The  exterior  of  the  room  should  be  as  inconspicuous  as 
possible;  that  is  to  say,  it  should  be  decorated  to  harmonize 
with  the  rest  of  the   theatre,  or,  if  possible,   to   form   some 
ornamental  part  in  the  general  scheme  of  decoration. 

19.  It  should  be  placed  in  charge  of  a  thoroughly  competent, 
reliable  staff  of  operators,  possessed  of  both  practical  and  tech- 
nical  knowledge    of   the  art   of  projection,  supplemented   by   a 
good  fund  of  horse  sense.    No  application  for  position  as  oper- 
ator should  be  considered  unless  the  applicant  can  show  that  he 
has  had  at  least  one  year's  experience,  or  has  served  one  year's 
actual  bona  fide  apprenticeship  in  an  operating  room. 

The  foregoing  constitutes  what  might  be  termed  the  funda- 
mental essentials  of  operating  room  construction  and  equip- 
ment, but  a  detailed  explanation  is  essential  in  addition  to 
this. 

Operating  Room  Door. — The  door  of  the  operating  room 
should  not  be  less  than  2  feet  wide  by  6  feet  in  height,  and  it 


214 


MOTION    PICTURE    HANDBOOK 


must,  of  course,  be  of  fire-proof  material.  The  sliding  door  held 
normally  closed  by  gravity  is  best.  This  idea  is  illustrated 
in  Fig.  80. 


Figure  80. 

Operating  Room  Floor. — It  is  of  extreme  importance  that 
the  operating  room  floor  be  perfectly  solid,  rigid  and  entirely 
free  from  vibration. 


B 


Figure  81. 

Suppose  for  instance  your  operating  room  floor  vibrated 
evenly  all  over  just  1/64  of  an  inch.  This  means  your  whole 
picture  is  jumping  up  and  down  on  the  screen  precisely  that 
much,  and  on  the  whole  this  would  scarcely  be  perceptible. 


FOR   MANAGERS    AND   OPERATORS  215 

On  the  other  hand,  however,  let  us  suppose  the  floor  vibrated 
in  such  manner  as  to  move  the  lens  of  the  machine  up  and 
down  in  teetering  fashion  the  same  amount.  Assuming  a 
throw  of  100  feet  the  movement  would  then  be  very  percepti- 
ble indeed  on  the  screen.  It  is  illustrated  in  Fig.  81,  in  which 
A  is  the  crater  of  the  arc  and  B  the  objective  lens.  If  you 
move  A  down  1/64  of  an  inch  and  at  the  same  time  move  B 
up  1/64  of  an  inch  you  will  readily  see  what  will  happen  out 
at  the  screen  surface  one  hundred  feet  away.  The  dotted 
line  illustrates  it. 

Modern  practice  is  to  fill  in  with  not  less  than  six  inches 
of  rich  concrete  and  after  tamping  this  down  well  finish  the 
top  off  with  one  inch  of  cement,  the  same  as  is  used  for 
sidewalks.  But  let  me  caution  you  that  many  contractors 
will  use  a  cheap  cement  unless  you  specify  the  kind  and  see 
that  it  is  used.  The  result  of  using  this  cheap  cement  is  that 
it  constantly  wears  away  into  dust,  thus  keeping  everything 
in  the  operating  room  covered  with  dirt.  I  tyave  seen  many 
operating  rooms  made  that  were  nothing  short  of  an  outrage 
in  this  respect.  The  only  remedy  was  to  paint  them  with 
oil  paint.  It  is  also  well  to  see  that  the  cement  finish  is 
mixed  with  sand  in  proper  proportions.  Remember  that, 
strange  as  it  may  seem,  not  all  contractors  are  followers  of 
the  Golden  Rule,  and  sand  is  cheaper  than  cement.  Also 
after  the  job  is  done  the  novice  cannot  detect  the  swindle 
at  once;  he  may  never  detect  it,  in  fact,  but  simply  knows 
there  is  something  wrong  with  the  operating  room  floor. 

If  the  floor  is  built  of  concrete  and  cement,  and  the  precau- 
tions I  have  named  are  taken,  it  will  to  all  intents  and  pur- 
poses be  one  solid  block  of  stone  when  it  has  set,  and  you 
won't  have  any  vibration  at  all,  because  a  thing  of  that  kind 
is  too  heavy  to  vibrate. 

Ports. — There  must  be  one  observation  and  one  lens  port 
for  each  projector,  one  lookout  and  one  lens  port  for  the 
dissolver,  if  there  is  one,  and  a  combined  lens  and  observa- 
tion port  for  the  spot  light,  except  that  if  the  projector  be  a 
combined  picture  projector  and  dissolving  stereopticon,  then 
it  must  be  provided  with  two  lens  ports,  one  small  and  square 
or  round,  and  one  narrow  and  high. 

Locating  Lens  and  Observation  Ports. — There  is  a  right 
and  a  wrong  way  and  a  hard  and  an  easy  way  to  do  almost 
everything,  including  the  locating  of  lens  holes.  The  author 
has  seen  it  done  in  many  different  ways,  but  the  following 
method  "seems,  everything  considered,  easiest  and  best. 


216 


MOTION    PICTURE    HANDBOOK 


If  observation  port  holes  are  built  into  the  wall  and  made 
of  the  right  size,  it  will  require  extremely  accurate  work — 
more  accurate  than  is  likely  to  be  done  by  the  average  brick- 
mason,  concrete  or  hollow  tile  man  to  get  them  exactly  right. 
I  would  strongly  recommend  the  following  procedure. 

Lay  out  your  operating  room  wall  as  per  Fig.  82,  in  which 
A,  B,  are  machine  lens  ports,  and  C,  D,  observation  ports,  the 


Figure  82. 


NOTE:  Through  an  oversight  the  stereopticon  observation  port  was 
omitted.  It  should  be  8"  square,  located  at  convenient  height,  its 
center  about  5'  6"  from  the  floor. 


latter  designed  to  be  covered  by  a  sliding  port-shutter,  and 
E  the  stereopticon  lens  port.  It  will  be  observed  that  ports  A 
and  B  are  12  inches  square,  and  that  port  E  is  18  inches 
high  by  8  inches  wide,  which  is,  of  course,  far  in  excess  of 
actual  requirement. 

Taking,  for  example,  the  Simplex  projector  with  standard 
pedestal;  when  it  sets  level  its  lens  is  47^  inches  from  the 
floor,  and  this  is  approximately  the  height  of  the  lens  of 
other  modern  projectors.  It  will  be  observed  that  ports  A 
and  B  are  located  3  feet  center  to  center,  and  that  their  cen- 
ters are  18  inches  on  either  side  of  the  center  line  of  the 


FOR   MANAGERS    AND    OPERATORS 


217 


screen,  which  must  be  first  located  on  the  plan.  It  will  also 
be  observed  that  the  bottom  of  ports  A,  B  is  3  feet  from  the 
floor,  which  brings  their  center  42  inches  above  the  floor  line, 
whereas  the  lens  will  be  47/^2  inches  from  the  floor.  In 
most  cases,  however,  there  is  a  more  or  less  steep  pitch  in 
the  projection,  so  that,  in  ordinary  cases,  if  the  projector  be 
located  with  the  lens  20  inches  from  the  wall,  as  it  should 
be,  the  light  ray  will  strike  approximately  the  center,  or  even 
below  the  center  of  the  large  port. 

After  the  wall  has  been  built,  the  floor  finished,  projectors 
in  place  and  the  light  finally  projected  to  and  located  on  the 
screen,  and  the  machines  per- 
manently bolted  down,  insert 
a  piece  of  asbestos  millboard, 
3/8  or  1/2  inch  thick,  set  flush 
with  the  outside  edge  of  the 
wall,  as  per  A  in  detail  sketch, 
Fig.  83,  strike  the  arc,  project 
the  light  ray  on  this  board, 
mark  a  circle  around  the  light, 
cut  out  the  circle,  replace  the 
board  in  the  opening  and  ce- 
ment it  in  as  per  detail  sketch 
Fig.  83. 

Having  completed  this,  set 
another  board,  C,  Fig.  83,  flush 
with  the  inside  edge  of  the  Figure  83. 

wall,  and  proceed  as  before.  You 

will  then  have  your  lens  port  in  exactly  the  right  location 
and  precisely  the  right  size,  and  you  will  have  it,  too,  with 
a  minimum  amount  of  trouble. 

The  observation  ports  C  and  D,  you  will  observe,  are  12  by 
24  inches,,  with  their  bottom  located  4  feet  from  the  floor 
line,  and  their  center  16  inches  from  the  center  of  the  lens 
port.  These  ports  are  designed  to  be  covered  by  an  asbestos 
millboard,  or  metal  sliding  shutters,  as  per  Fig.  86,  the  detail 
of  which,  together  with  detail  of  grooves,  is  shown  in  Figs.  84 
and  86. 

Port  E,  Fig.  82,  is  the  stereopticon  lens  port,  and  is  treated 
the  same  as  ports  A  and  B,  except  that  there  will  be  two 
small  light  ray  holes  in  the  asbestos  millboard,  instead  of  one. 

This  is  the  easiest  method  of  locating  the  lens  ports,  and 
it  will  be  found  to  serve  perfectly,  I  think,  except  in  very 
rare  cases  where  there  is  a  perfectly  level  projection,  in  which 


218 


MOTION    PICTURE    HANDBOOK 


case  ports  A  and  B  should  be  located  6  inches  higher,  or 
where  there  is  an  extraordinary  steep  pitch  in  the  projection, 
in  which  case  ports  C  and  D  must  be  located  lower,  as  pos- 
sibly must  also  ports  A  and  B. 


Q, 

y 

X.-Jf 


*--i 


Figure  84. 

In  cases  of  very  steep  projection  the  height  of  the  ports 
may  be  located  as  per  Fig.  84.  First  locate  the  height  of  the 
operator's  eyes  when  seated  in  operating  position.  I  have 
assumed  this  to  be  4  feet  from  the  floor  and  3  feet  away 
from  the  wall,  at  A,  Fig.  84.  Now  measure  the  exact  dis- 
tance from  Point  A  to  the  bottom  of  the  screen,  using  the 
elevation  plan  of  the  theatre,  if  there  is  one,  also  the  exact 
vertical  height  from  the  bottom  of  the  screen  to  point  A, 
Fig.  84.  Draw  a  rough  plan,  to  scale,  by  laying  off  the 
height  of  the  operator's  eye  above  the  bottom  of  the  screen, 
and  the  horizontal  distance  to  the  screen.  Then  draw  line  S, 
Fig.  84,  extending  from  point  A  to  bottom  of  the  screen. 


FOR  MANAGERS  AND  OPERATORS 


219 


Having  done  this,  measure  from  the  operating  room  floor 
line  straight  up  to  where  line  S  bisects  the  line  of  the  front 
operating  room  wall,  and  that  will  be  the  bottom  of  your 
observation  port,  though  you  should  make  it  two  or  three 
inches  lower  than  the  actual  measurement  from  the  floor  to 
the  line.  The  lens  ports  may  be  laid  out  in  exactly  the  same 
way. 

Still  another  way  is  by  calculation.  This,  too,  is  shown 
in  Fig.  84,  in  which  I  have  assumed  that  the  bottom  of  the 
screen  is  20  feet  below  point  A,  and  80  feet  away.  Divid- 
ing 80  by  20  we  find  there  is  a  drop  of  one  foot  in  each  four 
feet  of  horizontal  distance,  so  that  by  measuring  four  feet 
horizontally  from  point  A  we  establish  point  T,  and  then 
measuring  down  vertically  one  foot  we  get  the  exact  pro- 
jection pitch,  and  thus  know  where  to  locate  the  bottom  of 
the  port. 

For  all  ordinary  cases,  however,  the  plan  first  described 
will  serve. 


Figure  85. 

THE  OBSERVATION  PORT 

The  hole  in  the  wall  itself  should  in  no  event  be  less 
than  12  inches  wide.  The  necessity  for  a  wide  port  is  illus- 
trated in  Fig.  85,  in  which  A  represents  the  eyes  of  the 
operator  located,  when  seated  or  standing  in  normal  opera- 
ting position,  from  2  to  3  feet  back  of  the  operating  room, 


220 


MOTION    PICTURE    HANDBOOK 


wall.  B-B  is  the  screen;  lines  X-X  represent  the  view  the 
operator  should  have  of  the  entire  screen,  and  would  have 
did  the  width  of  the  port  extend  from  C  to  D;  lines  Y-Y 
show  the  view  the  operator  actually  has  of  his  screen  if  the 
port  is  narrow  and  only  extends  from  E  to  F.  In  this  event 
he  is  compelled  to  bring  his  eyes  right  up  close  to  the  opening 
in  order  to  see  the  entire  screen,  and  that  is  a  bad  condition, 
from  any  and  every  point  of  view. 

/  know  of  no  other  one  thing  which  operates  to  produce  poor 
results  on  the  screen  to  as  great  an  extent  as  do  narrow  and 
badly  placed  observation  ports. 


Figure  86. 

With  his  eyes  right  up  close  to  the  wall,  the  operator  must, 
of  necessity,  at  least  to  a  certain  extent,  neglect  his  projec- 
tion machine  and  his  lamp.  Moreover: 

No  operator  wilt  stand  for  hours  with  his  face  glued  to  the 
wall,  watching  his  picture  continuously;  and  unless  it  is  watched 
continuously  and  closely  there  will  be  shadows  on  the  screen,  or, 
in  other  words,  there  will  be  faults  in  the  projection. 

That  is  a  proposition  which  is  not  a  subject  for  argument. 
It  is  a  statement  of  fact,  which  managers  will  do  well  to  rec- 
ognize and  consider  very  seriously. 


FOR    MANAGERS   AND    OPERATORS  221 

The  height  of  the  observation  port  is  a  much  harder  mat- 
ter to  determine.  If  the  ceiling  of  the  room  itself  be  high 
enough  to  allow  of  the  installation  of  a  sliding  port,  such  as 
that  illustrated  in  Fig.  86,  I  would  strongly  recommend  that 
the  hole  in  the  wall  be  12  inches  wide  by  24  inches  in  height, 
as  per  Fig.  82,  and  that  over  this  hole  there  be  installed  a 
movable  sihutter  made  of  ^  or  y2  inch  asbestos  millboard, 
or  of  metal,  if  preferred,  although  asbestos  board  is  better, 
behind  which  should  be  installed  the  regular  asbestos  or 
metal  fire  shutter,  both  sliding  in  grooves,  as  shown  in  Figs. 
84  and  86,  the  movable  shutter  to  be  hung  on  a  counter- 
weight. 

In  Fig.  86  the  shaded  portion  represents  the  movable 
shutter,  also  shown  at  B,  Fig.  84.  It  should  be  at  least 
14  inches  wide,  with  an  opening  not  less  than  6  by  12  inches. 
I  believe  the  illustrations  make  the  matter  perfectly  clear, 
but  in  order  to  use  this  kind  of  shutter  it  is  necessary  there 
should  be  head  room  above  the  opening  in  the  wall  sufficient 
to  allow  the  shutter  to  be  raised  so  that  upper  edge  of  open- 
ing Y,  Fig.  84,  will  come  to  the  top  edge  of  the  hole  in  the 
wall  at  Point  Z,  Fig.  84,  and  the  lower  edge  of  opening  Y 
go  down  to  the  lower  edge  of  the  hole  in  the  wall.  It  is  not 
necessary  that  this  shutter  raise  or  drop  far  enough  to  en- 
tirely close  the  opening  in  the  wall,  that  being  taken  care  of 
by  fire  shutter  G,  Fig.  84. 

In  Fig.  84  the  grooves  in  w.hich  the  shutters  slide  are 
omitted  in  the  main  drawing  in  order  to  show  other  things. 
They  may  be  made  from  small  angle  and  channel  iron, 
readily  obtained  from  dealers  in  structural  iron.  Any  hard- 
ware dealer  can  obtain  them  for  you.  What  is  perhaps  the 
most  convenient  method  is  to  secure  about  12  feet  of  \%- 
inch  angle  iron  and  the  same  amount  of  ^2-inch  channel 
iron  for  each  24-inch  observation  port,  and,  after  cutting 
to  proper  length,  bolt  the  channels  to  one  side  of  the  angle 
as  at  R,  Fig.  84.  This  leaves  the  other  side  of  the  angle  to 
be  fastened  to  the  wall.  If  properly  put  together  this  makes 
a  most  excellent  shutter  groove.  The  one  shown  at  R, 
Figs.  84  and  86,  is  designed  to  carry  the  movable  port  shutter 
and  the  fire  shutter  behind  it.  For  single  grooves  one-inch 
angle  iron, is  ample. 

The  whole  idea  of  the  movable  shutter  is  to  allow  port  Y, 
Fig.  84,  to  be  placed  in  any  desired  position,  to  suit  a  tall 
or  short  operator;  also  to  accommodate  a  man  when  either 
sitting  down  or  standing  up.  Many  authorities  Insist  on  the 


222  MOTION    PICTURE    HANDBOOK 

observation  port  being  not  more  than  4  or  6  by  12  inches. 
Now,  a  fixed  port  4  or  6  inches  high  would  be  extemely  awk- 
ward, since  if  placed  to  fit  a  five-foot  man  would  be  mighty 
bad  for  a  six-footer,  or  vice  versa,  so  they  try  to  get  around 
that  difficulty  by  standing  the  thing  on  end,  with  result  as 
shown  by  lines  Y-Y,  Fig.  85.  The  movable  shutter  enables 
the  theatre  owner  to  comply  with  the  demands  of  the  au- 
thorities in  this  respect,  and  still  have  a  port  which  is  excel- 
lent in  every  way.  It  is  a  shutter  which  appeals  to  common 
sense,  and  no  official  can  possibly  advance  any  valid  objec- 
tion to  it. 

The  careful  planning  and  locating  of  the  observation  ports, 
as  hereinbefore  set  forth,  will  require  a  little  thought  and  con- 
sume a  little  time,  but  if  you  locate  them  in  such  manner  that 
the  operator  will  be  continuously  inconvenienced  you  have  no 
right  to  expect  that  you  will  have  uniformly  high  class  results 
on  your  screen,  and  let  me  tell  you  you  probably  won't  have 
them  either. 

A  little  time  spent  in  careful,  intelligent  study  of  this  mat- 
ter of  planning  and  locating  the  observation  ports  will  place 
the  operator  in  position  to  give  you  much  better  service,  and 
he  will  do  it,  too.  Therefore  it  naturally  follows  that  the 
time  thus  expended  is  a  most  excellent  investment. 

The  stereopticon  observation  port  is  not  of  so  much  im- 
portance, and  a  six  or  eight  inch  square  or  round  hole  will 
do,  since,  ordinarily,  one  uses  the  stereo  but  a  few  minutes 
at  a  time,  and  can  put  up  with  some  inconvenience  if  neces- 
sary. The  stereo  lens  port  can  be  located  the  same  as  per 
directions  for  the  projection  machine  lens  holes,  but  in  the 
case  of  the  stereopticon  the  hole  in  the  wall  need  not  be  more 
than  8  inches  wide,  but  it  should  be  18  inches  high,  the  same 
to  be  filled  in  with  asbestos  board  afterward,  as  directed 
for  the  other  lens  ports. 

The  spot  light  port,  if  one  there  be,  should  be  located  with 
its  center  5  to  5^2  feet  above  the  top  of  the  floor,  and  should 
be  16  to  18  inches  in  diameter,  square  or  round,  as  preferred. 

Wall  Fire  Shutters.— Every  observation  port  and  vent 
opening  should  be  provided  with  a  fire  shutter  made  of  3/8 
inch  asbestos  millboard,  although  some  authorities  are  satis- 
fied with  16-gauge  sheet  metal.  Metal  is,  however,  not  as 
desirable,  I  think,  as  asbestos  board  for  this  purpose. 

In  Fig.  87  is  shown  the  proper  method  of  bracing  the 
wall  shutters  to  keep  them  perfectly  flat.  The  braces  are  of 


FOR   MANAGERS   AND    OPERATORS 


223 


1  by  J4-inch  iron  secured  to  the  shutter  either  by  short, 
heavy  screws  or  stove  bolts. 

The  proper  installation  of  these  shutters  together  with  an 
adequate  vent  flue  and  thoroughly  fire-proof  walls  offers 
not  only  absolute  protection  from  fire  damage  to  anything 
outside  the  operating  room,  but  also  against  the  probability 
of  alarm  on  the  part  of  the  audience.  This  latter  will 
not  be  accomplished,  however,  unless  the  fire  shutters  be  so 
made  that  they  will  close  the 
instant  a  fire  starts.  This  last  is 
of  supreme  importance.  It  is 
seldom  indeed  the  fire  itself 
which  causes  loss  of  life  or  in- 
jury to  an  audience.  It  is  the 
panic  which  almost  invariably 
follows  an  alarm  of  fire  where 
an  audience  is  gathered.  Ninety- 
nine  times  out  of  every  hun- 
dred there  are  abundant  time 
and  opportunity  for  every  one  in 
the  theatre  to  escape  with  perfect 
safety,  provided  the  audience 
acts  rationally,  but  the  fact  is  an 
audience  seldom  or  never  does 
remain  rational  or  sensible  when 
an  alarm  of  fire  is  given,  par- 
ticularly if  either  fire  or  smoke 
be  visible.  Given  a  glimpse  of 
fire  or  smoke,  as  a  general 
proposition  you  may  depend 
upon  an  audience  to  go  stark, 
raving  mad,  pile  up  in  a  heap 
and  kill  each  other  through 
trampling  or  suffocation. 

/    desire    to   strongly    impress 

upon  architects  and  moving  picture  managers  and  owners  that 
it  is  entirely  practical  and  feasible  to  prevent  any  glimpse  of 
fire  or  smoke  by  the  audience  when  a  film  catches  fire,  but  in 
order  to  accomplish  this  fire  shutters  must  be  installed  which 
will  automatically"  close  every  opening  in  the  operating  room 
wall  the  INSTANT  the  fire  starts. 

Depending  upon  the  operator  to  drop  the  shutters  is  by  no 
means  a  safe  proposition.  The  operator  is  but  human,  and 
when  the  film  catches  fire  he  is  very  likely  to  become  more 


Figure  87. 


224 


MOTION    PICTURE    HANDBOOK 


or  less  excited,  and  it  is  a  cold  fact  that  you  never  can  tell 
what  an  excited  man  will  do,  or  what  he  won't  do.  Therefore 
I  emphasize  the  fact  that  it  is  a  dangerous  mistake  to  allow 
the  installation  of  fire  shutters  in  any  other  way  than  approx- 
imately as  hereinafter  described. 

Fig.  88  is  a  diagrammatic  representation  of  the  front 
operating  room  wall.  The  door  is  not  located  in  the  front 
wall  because  it  should  be  there,  but  merely  for  convenience 
in  showing  the  proper  arrangement  of  the  master-cord,  which 
should  terminate  in  ring  A,  held  by  an  ordinary  heavy  spike, 


Figure  88. 

nail,  or  bolt,  driven  into  the  wall  beside  the  latch  of  the 
door. 

This  whole  proposition  hinges  on  the  kind  and  location  of 
the  fuse  links.  The  master-cord  is  cut  into  sections,  and  these 
sections  are  joined  together  with  fuse  links,  located  over  each 
machine  magazine,  the  film  box,  and  over  the  rewind  table  in 
the  rewind  room.  These  fuse  links  may  be  of  160  degrees  fuse 
metal,  but  preferably  should  be  of  film,  as  shown  in  Fig.  88, 
in  which  the  fuse  clamps  are  drawn  out  of  all  proportion  as  to 
size  in  order  to  show  the  thing  more  clearly. 

In  Fig.  88  the  dotted  line  represents  the  master-cord, 
which  is  stretched  from  point  A  to  point  B,  as  shown,  though 
the  cord  may  be  carried  in  any  other  convenient  way,  pro- 
vided only  that  the  links  be  located  with  relation  to  the 
machine  magazines,  film  box,  and  rewind  substantially  as 
shown.  The  master-cord  may  be  of  heavy  cord  of  such  nature 


FOR    MANAGERS   AND    OPERATORS 


225 


that  it  will  not  stretch,  or  it  may  be  of  No.  22  copper  wire, 
provided  some  unthinking  official  does  not  object,  The  film 
links  over  machine  magazines  should  not  be  more  than  12  or 
less  than  6  inches  long,  and  should  not  be  more  than  3  inches 
above  the  top  of  the  magazine.  The  same  is  true  of  the  link 
over  the  film  box.  The  one  in  the  rewind  room  may  be  of 
convenient  length,  but  there  must  be  distance  enough  between 
clamp  Y  and  insulator  Z  to  allow  the  master-cord  to  slack 
sufficiently  to  let  all  the  shutters  go  clear  down.  If  this  distance 
be  too  small  there  is  danger  that  clamp  Y  will  strike  hole  Z 
before  the  shutters  have  entirely  dropped. 


Figure  89. 

The  detail  of  the  method  of  clamping  the  film  to  the  cord 
is  shown  in  Fig.  89,  as  is  also  the  details  of  one  method  of 
attaching  the  fuse  link  over  the  upper  machine  magazines. 
Rings  should  not  be  used  in  place  of  angle  studs  X,  because  in 
that  case  when  the  film  lets  go  the  clamp  might  catch  in  the 
ring  and  prevent  the  shutters  from  dropping,  whereas  with 
angle  studs  when  the  master-cord  slacks  it  instantly  drops  down 
off  the  studs. 

If  metal  fuse  links  are  used  they  should  be  located  ap- 
proximately the  same  as  the  film  links  shown.  Angle  studs 
X  may  be  made  by  obtaining  heavy  screw  hooks,  such  as 


226  MOTION    PICTURE    HANDBOOK 

housewives  use  to  screw  into  the  ceiling  to  hold  the  family 
bird  cage,,  etcetera,  but  the  hook  should  be  straightened  out 
until  it  stands  at  approximately  right  angles  to  the  screw, 
and  the  end  should  point  downward,  not  up,  when  it  is  final- 
ly in  position.  The  upright  bolt  attached  to  the  magazine 
around  which  passes  the  film  link,  or  the  master-cord  if  a 
metal  link  is  used,  should  be  made  of  ->6  or  l/2  inch  iron, 
flattened  at  one  end  and  attached  to  the  magazine  by  stove 
bolts,  as  shown. 

Having  arranged  our  shutter  cord  the  rest  is  simple.  The 
individual  shutters  are  raised  and  attached  to  the  master- 
cord  by  their  own  individual  cords,  which  terminate  in  a 
hook  designed  to  attach  to  the  master-cord.  The  master- 
cord  remains  permanently  in  place.  It  is  never  touched 
except  possibly  to  tighten  it  if  it  gets  slack.  The  shutters 
are  raised  one  at  a  time  in  the  morning  and  lowered  one  at 
a  time  at  night. 

I  believe  that  with  what  has  been  said  and  the  aid  of  Figs. 
88  and  89,  you  will  be  able  to  understand  this  matter  thor- 
oughly. 

The  whole  proposition  is  to  place  the  fuse  links  where  a 
fire,  either  af  the  film  box,  the  rewind  table  or  at  either 
machine,  will  INSTANTLY  strike  one  of  them,  thus  sever- 
ing the  master-cord  and  dropping  all  the  shutters  before  there 
is  any  smoke  or  blase  visible  to  the  audience.  Incidentally,  how- 
ever, it  is  exceedingly  important  that  the  bottom  stop  upon 
which  the  shutters  fall  be  heavily  padded  with  shredded 
asbestos,  since  if  the  shutters  fall  on  anything  hard  they 
will  make  an  awful  clatter  and  direct  the  attention  of  the 
audience  straight  to  the  operating  room — the  very  last  thing 
to  be  desired. 

It  will  be  observed  that  by  this  system  the  operator  can 
also  drop  the  shutters,  since  ring  I  is  placed  on  a  headless 
spike  right  beside  the  latch  of  the  operating  room  door.  If 
the  vent  flue  be  of  the  open  type,  then  shutter  D  should  be 
we:'4'hted  so  that  it  will  remain  normally  open,  and  it  must 
only  be  allowed  to  be  closed  by  a  cord  attached  to  the 
master-cord  by  means  of  a  hook,  the  result  being  that  when 
the  master-cord  is  slacked  and  the  shutters  closed  the 
damper  automatically  swings  open. 

An  operating  room  thus  equipped  is,  I  firmly  believe,  as 
safe  as  it  is  possible  to  make  it. 

There  is  no  earthly  sense  in  installing  metal  fuse  links  in 
the  shutter  cords,  and  locating  these  links  at  or  near  the  ceiling, 


FOR    MANAGERS    AND    OPERATORS  227 

as  is  done  in  nine  cases  out  of  ten.  Should  a  fire  occur  with 
the  fuse  links  thus  located,  by  the  time  they  become  sufficiently 
heated  to  melt  there  would  probably  be  very  little  use  in  closing 
the  shutters  at  all,  because  the  audience  would  most  likely  have 
seen  the  smoke  and  blase  and  be  piled  up  in  a  heap,  climbing 
over  each  other  in  their  mad  endeavor  to  escape  a  fancied 
danger.  •» 

There  are  those  who  may  argue  that  the  shutters  should 
be  dropped  gently,  and  that  this  can  only  be  done  by  the 
operator;  that  if  dropped  suddenly  as  by  a  fuse  melting, 
there  will  be  a  slam  which  is  likely  to  attract  the  attention 
of  the  audience  to  the  operating  room,  since  even  with  the 
shutters  falling  on  pads  there  is  bound  to  be  some  noise  pro- 


^T/?/*» 

^ 

SI 


Figure  90. 

duced    when    from    two    to    eight   shutters    are    released    and 
allowed  to  drop  unrestrained. 

This  is  a  matter  concerning  which  there  may  well  be  hon- 
est difference  of  opinion,  but  the  writer  strongly  favors  very 
careful  padding  of  shutters,  as  per  Fig.  90,  and  carefully 
placed  fuses,  because  there  is  always  the  liability  of  an  ex- 
cited man  forgetting  to  drop  the  shutters;  also  if  the  oper- 
ator is  to  be  depended  on  why  place  any  fuse  at  all?  Better 
make  it  one  thing  or  the  other,  and  I  believe  fuses  are  the 
thing. 

The  Vent  Flue. — The  vent  flue  of  the  operating  room  is  an 
exceedingly  important  matter,  since  it  not  only  provides  ven- 
tilation, but  must  be  depended  upon  to  carry  the  fumes  and 


228  MOTION    PICTURE    HANDBOOK 

smoke  from  burning  film,  should  a  fire  occur.  The  vent 
flue  should,  where  possible,  pass  directly  from  the  operating 
room  ceiling  through  the  roof  to  the  open  air,  with  its  top 
not  less  than  3  feet  above  the  roof  and  protected  by  a  suit- 
able hood  to  prevent  rain  from  beating  in.  For  a  long  time 
the  author  favored  the  open  vent  flue,  as  against  the  instal- 
lation of  a  vent-flue  fan.  However,  further  and  careful  study 
of  the  subject  has  changed  his  views.  This  change  was 
largely  brought  about  through  realization  of  the  fact  that 
under  certain  conditions  it  is  quite  possible  the  draft  through 
an  open  vent  would  be  down  instead  of  up;  this  is  especially 
true  in  certain  locations,  or  when  the  wind  is  in  certain 
directions,  as  any  housewife  who  has  experience  of  a  smoky 
chimney  can  testify.  This  being  the  fact,  I  am  convinced 
that  a  fan  in  the  vent  flue  is  better  than  an  open  pipe. 
//,  however,  the  vent  pipe  is  of  the  open  type  it  should  have 
an  area  of  not  less  than  288  square  inches,  regardless  of  the 
size  of  the  room.  A  burning  film  will  make  just  as  much  smoke 
and  gas  in  a  small  room  as  it  will  in  a  large  one.  It  should  be 
provided  with  a  damper,  weighted  to  remain  normally  open,  and 
only  allowed  to  be  held  closed  by  a  cord  attached  to  the 
master-cord  of  the  fire  shutters  in  such  manner  that  when 
the  fire  shutters  are  closed  the  vent  flue  damper  automatically 
will  swing  open. 

If  a  fan  is  installed  in  the  vent  pipe  it  should  be  not  less 
than  16  inches  in  diameter  and  it  would  be  exceedingly  good 
practice  to  install  two  vent  pipes  and  two  fans  instead  of  one, 
so  that  in  case  one  of  the  fans  gets  out  of  order  there  will 
still  be  the  second  one  to  fall  back  on.  This  may  seem  like 
a  rather  expensive  precaution,  but  somehow  or  other  it 
seems  to  be  a  fact  that  when  a  thing  happens  it  usually  hap- 
pens just  as  the  wrong  time,  which,  applied  to  the  single  vent 
flue,  would  mean  that  a  fire  would  most  likely  occur  when 
the  fan  was  broken  down. 

It  is  essential  that  the  vent  flue,  if  made  of  metal,  be  thor- 
oughly and  completely  insulated  from  any  inflammable  sub- 
stance throughout  its  entire  length,  since  it  is  likely  to  get 
very  hot  if  there  is  a  serious  fire.  The  safest  plan  is  to 
make  a  double  pipe,  with  an  air  space  not  less  than  3  inches 
between  the  inner  and  outer  walls. 

Operating  Room  Ventilation. — The  ventilation  system  of 
the  operating  room  is  a  matter  of  much  importance.  It  must 
be  remembered  that  the  operating  room  is  often  located 
immediately  under  the  roof  of  the  building  and  in  any  event 


FOR    MANAGERS    AND    OPERATORS  229 

would  be  extremely  hot  in  summer  time.  Add  to  this  the 
heat  generated  by  a  powerful  arc  lamp,  and  perhaps  one  or 
two  rheostats,  and  you  have  a  condition  which  makes  good  ven- 
tilation absolutely  imperative.  It  must  also  be  remembered,  in 
this  connection,  that  air  taken  in  from  the  auditorium  will 
be  that  which  has  arisen  from  the  audience,  and  will  therefore 
not  only  be  the  very  warmest  in  the  house,  but  also  vitiated 
and  rendered  unfit  for  use  by  a  human  being.  Moreover,  if  it  is 
taken  in  entirely  through  the  lens  and  observation  ports  an 
unpleasant  draft  is  likely  to  be  created,  which  blows  directly 
in  the  operator's  face.  This  latter  may  be  stopped  by  install- 
ing glass  in  the  ports  (see  "Glass  in  Ports"  further  on),  but 
in  that  event  other  means  of  letting  in  air  must  be  provided, 
and  should  be  provided,  whether  glass  is  used  or  not.  This 
is  best  done  by  making  inlet  openings  near  the  bottom  of 
the  room,  the  same  connected  with  the  outer  air  at  any  con- 
venient point,  thus  supplying  the  room  with  fresh  air  instead 
of  hot,  foul  air  from  the  auditorium.  But  these  latter  openings 
should  be  provided  with  fire  shutters  which  will  close  auto- 
matically in  case  of  fire,  in  order  to  stop  the  draft.  The  heat 
of  the  room  may  also  be  largely  reduced  by  connecting  the 
top  of  the  lamphouse  to  the  operating  room  vent  flue  by 
means  of  a  3  or  4  inch  metal  pipe,  having  riveted  joints.  This 
pipe  must  be  provided  with  a  swing  joint  if  the  lamphouse 
must  be  shoved  over  to  accommodate  a  stereopticon  lens. 
This  arrangement  also  operates  to  reduce  condenser  break- 
age by  providing  ample  ventilation  in  the  lamphouse.  It  is 
not  costly  to  install,  and  will  last  indefinitely.  Things  of 
this  kind  add  greatly  to  the  comfort  of  the  operator,  and 
hence  put  him  in  better  position  to  do  his  best  work.  The 
Massachusetts  law  contains  the  following  provision  concern- 
ing the  ventilation  of  operating  rooms,  which  is  worthy  of 
emulation : 

Operating  rooms  to  be  provided  with  an  inlet  in.  each  of  the  four 
sides,  said  inlets  to  be  15  inches  long  and  3  inches  high,  the  lower  side 
of  the  same  not  to  be  more  than  2%  inches  above  floor  level.  Said 
inlets  to  be  covered  on  the  inside  by  a  wire  net  of  not  greater  than 
%-inch  mesh;  netting  to  be  firmly  secured  to  the  asbestos  board  by 
means  of  iron  strips  and  screws.  In  addition  to  the  above  there  shall 
be  an  inlet,  in  the  middle  of  the  bottom  of  the  operating  room,  if  pos- 
sible; otherwise  in  the  side  or  rear  of  the  operating  room,  not  over  2% 
Inches  from  the  floor.  Said  opening  to  be  not  less  than  160  square 
inches  area  for  a  No.  1  operating  room,  200  square  inches  area  for  a 
No.  2  operating  room,  and  280  square  inches  area  for  a  No.  3  operating 
room;  connected  with  the  outside  air  through  a  galvanized  Iron  pipe 
with  a  pitch  from  the  operating  room  downward  to  the  outside  wall 
of  the  building.  The  opening  to  be  covered  with  a  hood,  so  arranged 


230 


MOTION    PICTURE    HANDBOOK 


as  to  keep  out  the  storm,  and  the  entrance  to  the  operating  room  to  be 
covered  with  a  heavy  grating  over  ^-inch  wire  mesh,  if  in  wall;  and 
arranged  with  damper  hinged  at  the  bottom,  and  rod  or  chain  to  hold 
said  damper  in  any  position.  Mesh  and  gratings  to  be  securely  fast- 
ened in  place,  those  in  the  walls  to  be  bolted  on  as  specified  for  the 
smaller  inlets. 

Note:     No.    1,   No.   2  and  No.   3   refer  to  the  size   of  rooms. 

The  same  law  contains  a  provision  for  a  vent  pipe  not  less 
than  12  inches  in  diameter  from  the  ceiling  of  the  operating 
room  to  the  open  air  outside  the  building,  or  to  a  special  in- 
combustible vent  flue.  In  a  two-machine  operating  room  this 

pipe  must  be  not  le«s  than 
16  inches  in  diameter  and 
in  a  three-machine  oper- 
ating room  it  must  be  not 
less  than  18  inches  in 
diameter. 

Glass     in    the     Ports.— 

Many  operators  are  now 
using  glass  in  both  lens 
and  observation  ports,  and 
this  is  a  practice  I  can  thor- 
oughly recommend,  provided 
the  glass  for  the  lens  port 
be  carefully  selected  and 
quite  thin.  I  think  an  old 
photographic  plate  would 
probably  be  ideal  for  the 
lens  port,  first,  of  course, 
cleaning  the  photographic 
emulsion  off  by  washing 
with  a  strong  solution  of 
hot  water  and  washing  soda. 
I  would  strongly  recommend 
that  the  observation  port  be 

surrounded  by  a  shadow1  box,  12  to  18  inches  in  depth, 
painted  dead  black  on  the  inside.  By  shadow  box  I  mean 
a  casing  such  as  you  would  have  if  you  knocked  the  bottom 
out  of  a  box  and  nailed  what  remained  over  the  port.  Where 
a  box  of  this  kind  is  not  used  there  is  more  or  less  reflection 
from  the  surface  of  the  glass,  and,  while  operators  say  that 
after  a  few  days'  use  they  do  not  notice  this,  and  that  it 
does  not  interfere  with  their  view  of  the  screen,  still  I  take 
the  liberty  of  doubting  the  correctness  of  this  statement.  I 


Figure  91. 


FOR    MANAGERS    AND    OPERATORS  231 

believe  they  would  be  better  able  to  see  faint  shadows  on 
the  screen  with  a  shadow  box  surrounding  the  port,  as  per 
Fig.  91. 

Operating  Room  Equipment. — Remembering  that  box  office 
receipts  of  a  moving  picture  theatre  depend  to  a  very  great 
extent  upon  excellence  of  the  results  upon  its  screen,  the 
wise  manager  will  bend  every  energy  toward  the  attain- 
ment of  artistic  projection,  and  will  use  every  reasonable 
endeavor  to  enable  his  operator  to  produce  high  class,  bril- 
liant, flickerless  pictures,  projected  at  proper  speed  to  bring 
out  and  emphasize  every  good  pointo  and  minimize  any 
weak  ones  there  may  be.  It  goes  without  saying  that  there 
is  small  probability  of  continuous  high  class  results  coming 
from  an  ill-placed,  small,  poorly  ventilated  operating  room, 
with  inferior  or  worn-out  equipment  in  charge  of  an  oper- 
ator of  mediocre  ability. 

It  also  follows  that  the  best  results  will  be  had  from  a  rightly 
located,  commodious,  well  ventilated  operating  room,  equipped 
with  up-to-date  machinery  and  placed  in  charge  of  a  thoroughly 
competent  operator,  who  will  keep  the  equipment  in  the  best 
possible  condition,  the  term  '"competency"  including  industry 
and  careful  attention  to  detail,  as  well  as  knowledge. 

The  mere  possession  of  knowledge  counts  for  little  or  noth- 
ing if  its  possessor  is  too  lazy  or  shiftless  to  apply  it  in  practice. 

In  planning  the  operating  room  the  architect  should  include 
two  small  clothes  closets  with  substantial  locks  thereon,  so  the 
operator  may  have  a  place  to  keep  his  private  belongings; 
also  it  is  well  to  have  two  tool  cabinets  which  may  be  locked 
up  securely — one  for  each  operator.  An  operator  should  have 
a  full  equipment  of  tools,  but  it  is  rather  discouraging  to 
provide  a  costly  kit  of  tools  and  then  be  compelled  to  leave 
them  at  the  mercy  of  any  one,  from  the  janitor  to  the  chance 
visitor,  to  say  nothing  of  the  other  operator,  who  perhaps  has 
none  of  his  own,  and,  moreover,  may  not  be  inclined  to  take 
the  best  care  of  those  belonging  to  others.  There  should  be 
drawers,  or  a  closet  in  which  to  keep  supplies,  such  as  car- 
bons, extra  condensing  lenses,  etc.,  though,  of  course  a  shelf 
will  serve,  and  if  the  walls  be  built  of  cement  it  is  a  compar- 
atively simple  matter  to  provide  cement  shelves  when  the 
room  is  built.  The  supply  closet  may  be  built  outside  of 
the  operating  room  if  desired.  There  should  also  be 
plenty  of  hooks  on  which  to  hang  wire,  etc.  It  is  an  ex- 
ceedingly unprofitable  thing  to  spend  time  hunting  for  a 
piece  of  wire  or  a  tool,  or  some  needed  repair  part,  when 


232  MOTION    PICTURE    HANDBOOK 

something  goes  wrong.  All  these  should  not  only  be  kept  in 
stock  but  be  kept  in  place,  where  the  operator  can  find  them 
instantly  when  they  are  needed.  For  instance:  fuses  should  be 
kept  near  the  fuse  cabinet;  when  a  fuse  blows  it  is  no  time  to 
be  rummaging  around  through  a  miscellaneous  lot  of  supplies 
to  get  a  new  one.  If  a  wire  burns  in  two,  possibly  stopping  the 
show,  it  is  no  pleasant  thing  to  have  to  look  through  a  pile  of 
miscellaneous  tangled  odds  and  ends  of  wire  to  find  what  you 
need.  The  point  I  am  making  is:  Have  a  place  for  everything 
and  everything  in  its  place.  This  is  not  likely  to  be  done,  how- 
ever, unless  proper  shelves,  hooks  and  closets  be  provided. 

//  an  operator  does  not  keep  things  in  order,  being  provided 
with  proper  places  in  which  to  keep  them,  then  he  is  not  the 
right  sort  of  man  to  have  in  charge  of  an  operating  room. 

There  should  by  all  means  be  a  wash  basin,  with  running 
water,  and  a  toilet  either  in  or  convenient  to  the  operating 
room;  both  of  these  are  quite  essential,  particularly  where 
only  one  operator  is  employed.  Often  something  will  go 
wrong  with  the  machine  and  the  operator  will  get  his  hands 
covered  with  oil  and  dirt  in  making  repairs.  If  there  is  no 
means  of  washing  them,  the  next  time  he  handles  a  piece  of 
film  there  is  likely  to  be  considerable  damage  done.  He  is  also 
very  apt  to  soil  everything  he  touches.  From  any  and  every 
point  of  view  a  wash  basin  ought  to  be  installed  in  or  near  the 
operating  room,  and  a  toilet  should  be  required  by  law,  since  in 
many  cases  the  operator  is  literally  chained  right  there  in  the 
operating  room  for  hours  at  a  stretch. 

An  one  end  of  the  operating  room  there  may  be  a  rewind- 
ing room,  the  two  separated  by  a  fire-proof  walland  door,  the 
shutter  master-cord  passing  through  this  wall  and  down  over 
the  rewinding  table,  with  a  fusible  link,  as  already  set  forth. 
If  there  is  a  motor  or  generator  set,  or  a  mercury  arc  rectifier, 
there  should  be  a  separate  room  provided  for  them  at  one  end 
of  the  operating  room.  These  machines  should  not  be  placed 
in  the  room  where  the  film  is  rewound,  and  a  mercury  arc 
rectifier  should  never  be  placed  in  the  operating  room  itself, 
because  it  makes  the  room  too  light,  and  it  is  thus  made  diffi- 
cult for  the  operator  to  discern  faint  shadows  on  the  screen. 

Supplies  for  the  Operating  Room. — I  cannot  imagine  a 
more  foolish  and  utterly  mistaken  policy  on  the  part  of  a 
manager  than  to  be  niggardly  in  the  matter  of  projection 
room  supplies.  On  the  other  hand  I  by  no  manner  of  means 
approve  of  the  operator  wasting  supplies  or  being  extrava- 
gant with  them. 


FOR    MANAGERS   AND    OPERATORS  233 

I  take  the  position  that  an  operator  who  cannot  be  trusted  to 
be  careful  and  economical  with  supplies  when  he  has  plenty  is 
not  a  fit  man  to  be  in  charge  of  an  operating  room. 

However,  in  this  connection  it  must  be  remembered  that 

A  good,  competent  operator,  who  understands  his  business 
and  is  allowed  to  do  things  as  they  should  be  done,  does  not 
wait  until  a  part  breaks  down  entirely,  thus  perhaps  stopping 
the  show  until  repairs  are  made;  he  renews  worn  parts  before 
the  break  comes. 

It  is  false  economy,  from  any  point  of  view,  to  try  to  get 
the  last  particle  of  wear  out  of  operating  room  equipment. 
Take,  for  instance,  asbestos  wire  lamp  leads.  Altogether  too 
many  operators  use  their  lamp  leads,  particularly  that  por- 
tion inside  the  lamphouse,  too  long.  Inside  the  lamp- 
house  the  wires  are  subjected  to  increasing  heat  from  the 
arc  as  they  approach  nearer  to  it,  and  as  the  temperature 
of  metal  rises  its  resistance  also  rises.  Copper  oxidizes 
under  the  action  of  heat,  and  where  a  wire  is  worked  close 
to  its  capacity  electrically,  and  you  add  a  high  temperature 
of  heat  from  an  outside  source,  the  effect  is  to  raise  the  re- 
sistance of  the  wire,  thus  lowering  its  carrying  capacity  and 
setting  up  still  more  heat  and  rapid  oxidization  and  deterio- 
ration. In  a  very  short  time  the  strands  turn  brown,  then 
dark  brown,  and  presently  if  you  bend  the  wire  near  the 
lamp  binding  post,  you  will  find  it  has  no  "spring";  it  is  like 
a  piece  of  string.  Under  this  condition  its  resistance  is  very 
high  and  it  is  consuming  wattage  which  in  a  few  hours'  time 
will  more  than  equal  the  cost  of  the1  wire.  If  you  strip  the 
asbestos  back  you  will  probably  find  its  strands  have  turned 
brown  for  a  considerable  distance.  ' 

I  would  recommend  that  where  No.  6  asbestos  stranded 
lamp  leads  are  used  they  be  cut  off  and  that  a  good,  heavy  wire 
connector,  D,  Fig.  30,  be  attached  and  then  connection  made 
from  that  to  the  lamp  with  a  short  piece  of  the  same  wire. 
Then  where,  say,  40  amperes  are  used,  once  every  week  re- 
move this  short  piece  of  wire,  throw  it  away  and  substitute 
a  new  piece.  This  will  cost  you  a  little  more  than  twenty 
cents,  but  it  will  save  that  much  or  more  in  current,  besides 
giving  a  better  light.  Where  less  than  40  amperes  are  used 
the  wire  can  be  continued  in  use  for  a  somewhat  longer  time. 
When  the  amperage  is  very  high,  larger  wire,  or  No.  6 
doubled,  should  be  used  inside  the  lamphouse. 

There  is  always  tendency  to  use  the  intermittent  sprocket 
of  the  projection  machine  too  long.  Intermittent  sprockets 


234  MOTION    PICTURE    HANDBOOK 

of  modern  projectors  are  very  carefully  made  and  hardened, 
but,  notwithstanding  this  fact,  in  the  course  of  time  the  con- 
stant wear  of  the  film  will  cut  a  notch  in  the  side  of  the 
sprocket  teeth  and  in  time  wear  them  into  a  hook  shape, 
which  has  tendency  to  produce  unsteadiness  in  the  picture, 
as  well  as  do  serious  injury  to  the  film  itself.  Therefore,  this 
being  the  fact,  it  would  be  true  economy  to  replace  the  in- 
termittent sprocket  before  the  teeth  show  any  appreciable 
wear  when  subjected  to  examination,  using  a  condenser  lens 
as  a  magnifying  glass. 

I  mention  these  two  examples  merely  as  typical,  and  place 
them  in  evidence  as  showing  that  it  does  not  pay  to  be  too 
economical  in  the  matter  of  operating  room  supplies;  also 
as  proof  that  lack  of  knowledge  often  causes  a  manager  to 
practice  what  is  in  effect  false  economy,  or,  in  other  words, 
practice  economy  which  is,  as  a  matter  of  fact,  exactly  the 
opposite.  It  never  pays  to  compel  the  operator  to  use  worn 
parts,  since  worn  parts  always  tend  to  injure  results  on  the 
screen. 

Managers  would  do  exceedingly  well  to  secure  an  operator  in 
whose  judgment  they  have  confidence,  and,  having  done  so, 
alloiv  him  reasonably  free  hand  in  the  matter  of  supplies. 

It  is  an  absolute  fact  that  failure  to  grasp  this  simple  idea, 
and  apply  it  in  practice,  is  causing  the  moving  picture  industry 
many,  many  thousands  of  dollars  every  year  through  loss  of 
business.  Tens  of  thousands  of  people  would  be  more  regular 
patrons  of  moving  picture  theatres  if  the  pictures  in  those 
houses  were  placed  on  the  screen  in  the  best  possible  manner, 
but  placing  the  picture  on  the  screen  in  the  best  possible  man- 
ner is  utterly  impossible  to  the  operator  ivho  is  not  supplied 
with  proper  equipment  or  with  needed  repair  parts. 

In  the  operating  room  should  be  an  ample  supply  of  car- 
bons, wire  of  the  various  kinds  used,  plenty  of  fuses  of  the 
different  sizes  and  kinds  used,  slide  cover  glasses  (clean, 
not  dirty),  stereopticon  mats  and  gummed  binder  strips, 
extra  parts  for  the  intermittent  movement,  and,  if  it  be  a 
Power,  Motiograph  or  Simplex  machine,  then  an  entire  intermit- 
tent movement,  including  the  framing  carriage,  already  assembled 
and  ready  to  slide  into  place  in  the  machine;  extra  machine 
bushings  for  intermittent  and  cam  shaft  bearings,  extra  con- 
densers, and,  in  fact,  everything  likely  to  be  needed. 

In  the  room  should  be  some  sort  of  a  water-tight,  metal 
receptacle  of  such  form  that  it  will  not  be  easily  upset,  this 
to  be  kept  half  full  of  water  to  receive  hot  carbon  butts.  If 
the  operating  floor  is  covered  with  iron  (bad  practice,  but 


FOR    MANAGERS    AND    OPERATORS  235 

still  followed  in  some  localities)  it  should  be  covered  with 
insulating  material,  such  as  cork  matting,  rubber  matting  or 
linoleum,  or  at  least  there  should  be  an  insulating  mat  of 
ample  size  on  the  operating  side  of  both  machines  and  the 
stereopticon,  otherwise  the  operator  is  most  likely  to  be 
subjected  to  unpleasant  shocks,  though  this  does  not  hold 
true  if  the  Iamphouse.be  thoroughly  and  effectively  grounded 
to  the  floor. 

Operator's  Chair. — Some  managers  insist  upon  the  oper- 
ator standing  up,  and  will  not  allow  a  chair  in  the  room. 
With  all  due  respect  to  them,  that  is  pure,  unadulterated 
nonsense.  Some  men  prefer  to  stand  up,  but  to  other  men 
standing  several  hours  continuously  on  their  feet  is  a  tre- 
mendous hardship.  The  writer,  for  instance,  could  not 
and  would  not  do  it.  At  the  end  of  two  hours  he  would  be 
too  badly  exhausted  to  do  good  work.  Anyhow,  there  is  no 
earthly  reason  why  the  operator  should  not  be  seated  com- 
fortably at  his  machine.  If  the  observation  port  be  properly 
made,  so  that  he  can  view  his  picture  from  that  position, 
there  is  absolutely  no  reason  whatever  to  suppose  he  won't 
do  just  as  good  work  seated  as  Wihen  standing  up. 

As  a  matter  of  fact  the  operator  is  very  likely  to  do  better 
work  when  seated  than  when  standing,  because  when  standing 
there  is  always  the  temptation  to  move  around,  whereas  if 
seated  at  the  machine  he  is  likely  to  remain  right  there  in  front 
of  the  observation  port  where  he  ought  to  be,  and  where  he 
must  be  to  deliver  the  best  results.  It  is  therefore  good  policy 
not  only  to  allow  the  operator  to  be  seated  at  the  machine,  but 
to  provide  a  comfortable  chair,  or  at  least  a  stool  of  proper 
height. 

Ammeter  and  Voltmeter  in  the  Operating  Room. — It  is,  m 

the  judgment  of  the  author,  an  exceedingly  good  investment 
to  locate  an  ammeter  or  voltmeter,  particularly  the  former, 
in  such  position  that  it  will  be  constantly  in  front  of  the 
operator  when  he  is  in  operating  position  at  the  machine, 
the  same  to  be  connected  to  the  operating  room  feeders,  so 
as  to  indicate  all  current  used  in  the  room.. 

There  is  a  certain  point  at  which  the  projection  arc  will 
produce  maximum  illumination  with  a  minimum  current 
consumption.  Just  a  little  movement  of  the  carbons  away  from 
this  position  will  jump  the  current  consumption  by  anywhere 
from  5  to  20  per  cent.,  without  in  any  way  increasing  the  light 
brilliancy — in  fact  it  is  likely  to  decrease  it.  With  an  am- 


236  MOTION    PICTURE    HANDBOOK 

meter  placed  directly  in  front  of  the  operator  he  is  able  to, 
and,  if  a  careful  man,  will  maintain  his  arc  at  the  point  of 
maximum  brilliancy  with  minimum  current  consumption.  I 
believe  that,  in  the  average  theatre,  an  operating  room 
ammeter,  if  properly  located,  will  pay  for  itself  in  a  very 
short  time.  A  good  ammeter  may  be  had  at  from  twelve  to 
fifteen  dollars. 

The  method  of  connecting  an  ammeter  or  voltmeter  is  set 
forth  in  Fig.  92. 


Figure  92. 

Anchoring  the  Machine. — It  is  absolutely  essential  to 
steadiness!  of  the  picture  on  the  screen  that  the  machine 
itself  be  rigid,  and  without  the  least  vibration.  Most  modern 
projectors  have  tables  or  pedestals  sufficiently  solid  to  re- 
quire no  additional  anchoring,  provided  the  floor  itself  be 
without  vibration.  However,  there  are  still  a  number  of  old 
style  tables  in  use,  and,  for  the  benefit  of  the  users  thereof, 
I  illustrate  an  excellent  table  anchor  in  Fig.  93. 

In  Fig.  93,  A  is  a  piece  of  1^4-inch  pipe,  at  the  top  of 
which  is  a  flange  with  a  right-hand  thread  and  at  the  bot- 
tom a  flange  with  a  left-hand  thread.  Pipe  A  is  cut  just 
long  enough  barely  to  clear  the  floor  and  ceiling  when  the 
flanges  are  not  on..  Now  screw  the  flange  on  and  with  a 
Stillson  wrench  turn  the  pipe  counter  clockwise,  which  will 
have  the  effect  of  forcing  the  top  flange  against  the  ceiling 
and  the  bottom  flange  against  the  floor,  thus  firmly  anchor- 
ing pipe  A,  to  which  the  machine  table  is  then  attached  by 
means  of  part  B.  The  front  of  the  table  may  then  be 
anchored  to  the  front  wall  as  shown.  Legs  of  tables  of  the 
tvpe  shown  in  Fig.  93  should  be  set  in  iron  sockets,  or,  in 
rneir  absence,  be  placed  in  an  indentation  made  in  the  floor. 


FOR  MANAGERS  AND  OPERATORS 


237 


These  tables  are,  however,  out  of  date,  and  are  rapidly  being 
discarded. 

Tools. — The  operator  should,  as  has  been  remarked,  be  in 
possession  of  a  kit  of  tools  enabling  him  to  do  ordinary  re- 
pair jobs.  Such  a  kit  of  tools  cost  several  dollars,  but  it  is 
a  good  investment.  The  manager  is  likely  to  have  more 
respect  for  the  operator  who  owns  a  good  tool  kit  than  for 
the  one  who  shows  up  with  a  ten-cent  screw-driver  in  one 


,~L   shaped  piece  to 

y    front  end 
fable'   to   froni 
H    of  bootk 


figure  93. 

pocket  and  a  pair  of  broken  pliers  in  another.  In  the  second 
edition  of  the  Handbook  I  gave  a  list  of  tools,  to  which  I 
see  no  reason  for  either  subtracting  or  adding,  except  in 
the  item  of  a  small  hand-bellows,  which  is  a  very  convenient 
tool  with  which  to  blow  dust  and  dirt  from  around  switches, 
and  from  around  the  pole-pieces,  armature  and  places  where 
a  brush  cannot  be  used  on  a  motor  or  generator.  This  is  a 
thing,  however,  which  does  not  really  belong  to  the  operator's 
kit,  but  should  be  supplied  by  the  manager,  and  should  have 
a  place  in  every  operating  room.  It  is  a  necessity  where  a 


238  MOTION    PICTURE    HANDBOOK 

motor   generator   set   is  used.     The   following   is   the   list  of 
tools: 

One  pair  "button"  pliers  8  or  10  inch;  one  pair  8  or  10  inch 
lineman's  side  cutting  pliers  (I  leave  the  matter  of  size  open, 
as  some  prefer  one  and  some  the  other);  one  pair  8  or  10 
inch  gas  pliers;  one  large  and  one  medium  screw-driver;  one 
screw-driver  with  good  length  of  carefully  tempered  blade 
for  small  machine  screws,  to  be  heavily  magnetized  so  as  to 
jhold  small  screws;  one  pair  of  pliers  for  notching  film,  see 
Fig.  76;  one  small  riveting  hammer;  one  claw  hammer;  one 
small  cold  chisel;  one  medium-sized  punch;  one  very  small 
punch  for  star  and  cam  pins;  one  small  pair  tinner's  snips; 
pair  blunt-nose  film  shears  (such  as  clerks  use);  one  small 
gasoline  torch  for  soldering  wire  joints;  one  :hack-saw.  With 
this  kit  you  will  be  able  to  do  almost  any  ordinary  job,  but 
you  will  have  use  for  them  all.  In  addition  to  the  above  the 
house  manager  should  furnish  one  8  and  one  10  inch  flat  file, 
one  $/%  round  file,  one  8  inch  "rat  tail"  file,  a  small  benc'h 
vise  with  anvil  and  some  soldering  flux  and  solder  wire. 

In  this  list  there  is  nothing  which  will  not  be  found  of  use, 
and  many  operators  will  desire  and  acquire  a  more  elaborate 
kit. 

Tools  in  Order. — It  is  of  the  utmost  importance  that  the 
operator's  tools,  be  they  many  or  few,  be  kept  in  order, 
neatly  arranged  on  the  wall,  the  screw-drivers  and  pliers 
within  handy  reach  from  operating  position.  One  of  the 
most  reprehensible  habits  possible  is  that  of  dropping  tools 
when  one  has.  finished  using  them  and  letting  them  lie  until 
needed  again. 

It  would  be  hard  to  estimate  how  many  thousands  of  times 
moving  picture  theatre  audiences  have  sat  in  the  dark,  wait- 
ing patiently  while  an  operator  searched  around  looking  for 
the  pliers,  screw-driver,  or  other  tool  needed  to  make  a  repair, 
which  he  had  thrown  down  wherever  he  happened  to  use  it 
last.  Often  I  have  gone  into  operating  rooms  and  found  the 
operator's  tools  lying  on  the  floor  in  a  jumbled  pile  under- 
neath the  machine.  This  kind  of  thing  is  not  only  exceed- 
ingly unworkmanlike  but  decidedly  sloppy.  The  man  who 
does  things  that  way  is  never  likely  to  make  any  large  suc- 
cess, either  of  operating  or  anything  else. 

My  advice  to  the  operator  is~  have  a  good  kit  of  tools  and 
keep  them  neatly  arranged  and  in  perfect  order. 


FOR    MANAGERS   AND    OPERATORS  239 

My  advice  to  ihc  manager  is  to  discharge  the  operator  who 
is  satisfied  to  own  a  pair  of  pliers  and  a  screw-driver,  or  who, 
having  other  tools,  does  not  keep  them  in  order.  If  he  is  un- 
workmanlike in  so  important  an  item,  it  is  likely  he  will  be  un- 
workmanlike in  other  things  zvhich  zvill  reflect  directly  on  the 
screen  in  the  shape  of  faulty  projection. 

Announcement  Slides. — It  is  frequently  necessary  to  make 
announcements  to  the  audience.  There  are  a  great  many 
different  ways  in  which  very  good  appearing  slides  can  be 
hastily  prepared.  There  are  inks  on  the  market,  in  several 
colors,  with  which  one  may  write,  using  an  ^ordinary  pen,  on 
clean,  plain  glass,  just  the  same  as  he  could  write  on  paper. 
There  are  also  a  number  of  slide  coatings  for  sale  on  which 
writing  may  be  done  with  a  sharp  pointed  instrument. 
These  slide  coatings  are  particularly  to  be  desired  for  any 
slide  which  must  be  made  on  the  spur  of  the  moment,  by 
reason  of  the  fact  that  a  number  of  them  can  be  got  ready 
and  laid  tip  on  a  shelf  in  a  pile  where  they  will  keep  in- 
definitely. If  anything  happens  and  you  wish  to  say  some- 
thing to  the  audience,  the  operator  can  write  on  these  slides 
with  anything  having  a  sharp  point.  For  instance,  sup- 
pose something  occurs  that  will  cause  a  delay  of  two  min- 
utes. Within  five  seconds  the  operator  can  write  on  one  of 
these  slides  ".Unavoidable  Delay  of  Two  Minutes,"  stick  it 
in  the  stereopticon  and  project  it  to  the  screen.  The  audi- 
ence will  then  be  satisfied  to  wait  for  that  length  of  time. 
I  only  suggest  this  as  one  possible  way  in  which  slides  of 
this  kind  may  be  utilized.  They  should  be  kept  in  the  oper- 
ating room  ready  for  instant  use.  Please  understand  in 
this  I  am  not  referring  to  program  slides  which  the  man- 
ager himself  will  wish  to  prepare,  but  merely  those  designed 
to  be  used  for  emergencies. 

WIRING  THE  OPERATING  ROOM 

The  wiring  of  the  operating  room  is  a  matter  which  should 
be  carefully  planned  before  the  construction  of  the  room  is 
begun,  particularly  if  the  walls  are  to  be  of  concrete  or 
brick. 

The  operating  room  feeders  must  be  large  enough  to 
carry  the  entire  load  of  the  operating  room.  That  is  to  say, 
if  there  are,  for  instance,  two  projection  arc  lamps,  a  dis- 
solving stereo,  a  spot  light  and  four  incandescent  lamps,  then 
the  operating  room  feed  wires  must  be  large  enough  to  carry 


240  MOTION    PICTURE    HANDBOOK 

the  combined  amperage  of  all  these  lamps  when  they  are  all 
burning.  True,  they  probably  never  will  be  burning  all  at 
one  time,  but  that  does  not  alter  the  fact  that  the  wires  must 
be  able  to  supply  them  all  without  overload. 

Note. — When  A.  C.  circuits  are  run  in  conduit  always  place 
both  wires  of  the  circuit  in  the  same  conduit.  If  they  be  run  in 
separate  conduits  a  highly  objectionable  inductive  effect  will 
be  set  up  in  the  conduit. 

In  order  to  figure  the  necessary  amperage  capacity,  pro- 
ceed as  follows:  First  estimate  the  combined  amperage. 
Suppose  there  are  two  projectors  and  you  propose  to  use  40 
amperes  from  .a  HO  volt  line  through  resistance.  This  would 
call  for  40  +  40  =  80  amperes  at  the  two  projector  arcs. 
Suppose  there  is  a  dissolving  stereo  which  requires  15  am- 
peres per  light,  or  a  total  of  30  amperes,  a  spot  light  taking 
15  amperes  and  incandescent  taking  5  amperes;  thus 
gO-|-30-f  15  +  5  =  130  amperes.  Turning  to  Table  1,  Page 
42,  we  find  that  if  the  feeders  be  two  wire,  it  will  require 
00  R.  C.  wire  to  carry  that  amount  of  current. 

If,  however,  the  feeders  are  three  wire,  then,  since  when 
the  lamps  were  all  burning  the  arc  would  burn  in  series  on 
220  instead  of  110  (See  three-wire  system,  Page  56),  the  am- 
perage requirement  would  be  cut  in  half  and  it  would  only 
be  necessary  to  have  No.  5  feeders. 

Again,  if  all  the  lamps  are  to  be  operated  from  a  motor 
generator  set,  rotary  converter,  mercury  arc  rectifier,  or  on 
current  taken  through  an  economizer  (transformer),  then 
the  operating  room  feeders  need  only  be  large  enough  to 
supply  the  primary  capacity  of  these  devices,  or  the  com- 
bined amperage  of  the  arcs  reduced  from  secondary  to 
primary,  provided  this  apparatus  be  in  the  operating  room. 

The  operating  room  feeders  should  be  brought  in  at  the 
most  convenient  point,  through  conduits,  and  carried  to  a 
metal  switchboard  cabinet.  As  has  been  already  set  forth 
under  title  "Operating  Room,"  the  circuit  conduits  should  be 
laid  before  the  room  is  built,  and  be  built  into  the  wall,  floor 
and  ceiling.  There  is  no  sense  in  having  the  operator  stum- 
bling over  a  conduit  laid  on  the  floor;  also,  a  conduit  laid  on 
wall  and  ceiling  looks  unworkmanlike.  It  looks  like  a  "half 
baked"  job.  Do  the  thing  right  and  embed  the  conduit  in 
the  wall  when  building  the  room,  carefully  planning  the  out- 
lets. 

The  main  operating  room  switchboard  cabinet  should  con- 
tain (a)  main  feeder  switch  A,  and  fuses  B,  Fig.  94, 


FOR    MANAGERS    AND    OPERATORS  241 


Figure  94. 


242  MOTION    PICTURE    HANDBOOK 

carrying  the  entire  operating  room  load;  (b)  a  small  switch 
and  fuses,  C,  Fig.  94,  carrying  the  operating  room  incan- 
descent circuits;  (c)  cutout  blocks  D,  E,  F  (as  many  as 
needed),  carrying  fuses  for  the  various  circuits,  and,  if  de- 
sired, switches  also.  In  the  drawing,  Fig.  94,  we  will 
assume  circuits  1  and  2  to  supply  the  projection  machine 
arcs,  circuit  3  and  4  the  dissolving  stereo,  circuit  5  the  spot 
light,  and  circuit  6  the  incandescents. 

The  switchboard  plan  shown  in  Fig.  94  is  merely  illus- 
trative. The  board  may  be  built  up  to  accommodate  as  many 
or  as  few  circuits  as  may  be  necessary.  The  cutout  blocks 
shown  may  be  porcelain  base  cutouts  with  switches,  similar 
to  those  illustrated  in  Fig.  18,  Page  72;  they  may  be 
porcelain  base  cutout  blocks  without  a  switch,  as  shown,  or 
they  may  be  slate  base  switches  with  fuse  receptacles. 

Where  the  three-wire  system  is  used  to  feed  the  operating 
room  and  connection  is  made  to  the  neutral,  the  projection 
arcs  should  be  connected  on  opposite  sides.  It  is,  of  course, 
impossible  to  balance  the  operating  room  load  on  a  three- 
wire  system  because  ordinarily  only  one  projection  arc  will 
be  burning  at  a  time,  but  suppose  you  connect  both  lamps 
of  your  dissolver  to  one  side,  then  when  the  dissolver  is  in 
use,  instead  of  the  load  being  balanced  there  is  approxi- 
mately 30  amperes  on  one  side  and  nothing  on  the  other, 
which  is  bad.  Then,  too,  if  both  projection  lamps  are  con- 
nected to  one  side,  when  the  arc  of  the  idle  machine  is  struck 
to  heat  the  carbons,  before  switching  over  to  a  new  reel,  for 
a  short  time  the  entire  load  of  both  projectors  is  on  one  side, 
meaning  that  anywhere  from  60,  80,  90  or  even  100  amperes 
of  current  would  be  on  one  side,  and  this  much  of  an  un- 
balanced effect  would  be  felt  by  a  good  sized  power  plant. 
To  sum  this  matter  up: 

Where  a  three-wire  system  is  used  to  feed  the  operating  room, 
connect  projection  arcs  to  opposite  sides  and  connect  dissolver 
lamps  to  opposite  sides,  except  where  mercury  arc  rectifiers, 
motor  generators  or  economizers  are  used,  in  which  case  it 
is  much  better  to  leave  the  neutral  idle  and  connect  only  to 
the  outside  wires,  purchasing  your  motor  generator  or  econo- 
mizer with  that  end  in  view — with  a  220  volt  motor.  Mer- 
cury arc  rectifiers  may  be  used  for  either  110  or  220. 

The  location  of  the  operating  room  switchboard  cabinet 
will  necessarily  be  determined  by  local  conditions,  but  use 
care  to  place  it  conveniently. 


FOR    MANAGERS    AND    OPERATORS  243 

There  is  nothing  to  be  gained  by  making  things  inconvenient 
for  the  operator,  and  there  is  much  to  be  lost  by  doing  so. 

As  to  the  main  operating  room  fuses,  I  would  suggest 
they  be  placed  as  s'hown  in  Fig.  94,  rather  than  on  the  other 
side  of  the  switch.  Inasmuch  as  the  operating  room  feed 
wires,  including  the  operating  room  main  switch,  is  pro- 
tected by  fuses  on  the  main  switchboard,  there  is  no  neces- 
sity for  protecting  it  further,  and  it  is  more  convenient  to 
install  fuses  at  B  if  the  fuse  block  is  "dead"  than  if  it  be 
"alive." 

In  some  cities  the  power  company,  will  not  allow  the  neu- 
tral of  a  three-wire  system  to  be  run  to  the  operating  room. 
This  compels  the  use  of  220  volts  which,  if  rheostats  are 
used,  is  very  wasteful  indeed.  The  reason  for  this  is  the 
heavy  unbalancing  effect  (already  explained)  of  the  projec- 
tion arcs.  It  is  quite  possible  that  this  unbalancing  effect 
might,  be  very  serious,  from  a  power  company's  point  of 
view,  particularly  in  a  small  city  where  there  are  a  number 
of  moving  picture  theatres  and  the  power  company's  genera- 
tors likely  to  be  pretty  heavily  loaded.  Supposing,  for  in- 
stance, one  side  of  a  street  main  supplies  five  moving  picture 
theatres,  each  having  two  machines  connected  to  the  same 
side  of  a  three-wire  system.  Now  suppose  it  happens,  as  it 
might  easily  happen,  that  the  operators  in  all  five  theatres 
chanced  to  be  changing  from  one  machine  to  the  other  at 
the  same  time,  and  all  struck  the  arcs  of  their  idle  machines 
at  the  same  moment.  This  would  mean,  assuming  that  all 
were  pulling  40  amperes  at  each  arc,  a  total  unbalance  of  400 
amperes  (five  theatres,  two  arcs  to  the  theatre),  which  would 
probably  put  everything  else  attached  to  this  same  generator 
out  of  business,  at  least  temporarily. 

Even  if  these  five  theatres  each  had  their  two  arcs  on 
opposite  sides,  when  only  one  arc  was  burning  it  would  mean 
an  unbalance  load  of  40  X  5  =  200  amperes,  so  you  see  the 
light  company  is  perfectly  justified  in  demanding  that  only 
the  outside  wires  be  used.  But  this  does  not  hold  good  if  cur- 
rent is  taken  through  resistance.  In  that  event  the  changing  to 
the  two  outside  wires  would  have  no  effect  at  all,  except  to 
load  both  generators  of  the  system  that  much  more  heavily. 
Instead  of  having  one  generator  pulling  an  unbalanced  load 
of  400  amperes,  as  before  set  forth,  if  connected  to  the 
two  outside  wires  through  resistance  both  generators  would 
be  pulling  a  load  equal  to  400  amperes  at  110  volts,  when 
all  arcs  were  burning,  therefore  the  only  thing  gained  is  a 


244 


MOTION    PICTURE    HANDBOOK 


big  additional   (double)   and   entirely  useless   waste   of  elec- 
trical energy. 

What  the  light  company  has  the  undoubted  right  to  do 
is  to  demand  that  the  projection  lamps  of  the  theatre  be 
connected  to  opposite  sides  of  a  three-wire  system  when 


Figure  95. 

current  is  taken  through  rheostats,  and  if  an  economizer, 
motor  generator,  rotary  converter  or  mercury  arc  rectifier 
be  used  that  the  supply  be  taken  from  the  outside  wires. 

In  Fig.  95,  the  typical,  and  in  some  ways  excellent  operat- 
ing room  of  the  Park  Theatre,  Bangor,  Me.,  is  illustrated. 
It  will  be  observed  that  the  projection  machine  circuits  are 
led  under  the  floor  and  up  to  an  outlet  immediately  under 


FOR    MANAGERS   AND    OPERATORS  245 

the  lamphouse,  which  is  exactly  as  it  should  be.  The  vent 
flue  seems  to  be  of  ample  size  and  well  located.  The 
switchboard  is  apparently  neatly  put  together,  but  should 
have  a  metal  cabinet  to  protect  it.  The  switch  and  volt- 
meter and  ammeter  near  the  ceiling  at  the  right  govern  a 
5  k.w.  motor  generator  set. 

The  work  bench  is  made  of  wood,  which  would  be  ob- 
jected to  in  many  cities,  though  the  objection  has  no  real 
basis.  There  is  about  ;as  much  danger  in  a  wooden  work 
bench  in  an  operating  room  as  there  is  in  a  pile  of  sawdust 
in  an  ice  house.  The  fuse  links  of  the  shutter  cord  are 
so  located  that  they  would  be  of  slight  value  in  case  of  fire. 
There  is  no  evidence  of  toilet  conveniences,  though  it  is 
possible  they  may  be  placed  near-by  but  outside  the  op- 
erating room.  The  tools  would  look  better  in  a  neat  rack 
over  the  work  bench,  instead  of  lying  on  the  bench. 

In  Fig.  96,  Fig.  97,  and  Fig.  98,  we  see  three  views 
of  a  most  excellent  operating  room  installation  at  the 
Monarch  Theatre,  Cleveland,  Ohio.  In  this  installation 
there  is  little  to  criticise.  The  fire  shutters  are  hung  from 
a  master-cord,  which  is  correct  practice.  As  shown  the 
master-cord  fuses  are  wrongly  placed,  but  I  am  informed 
that  since  the  picture  was  taken  the  fuses  have  been  car- 
ried down  under  the  magazine  and  placed  over  the  machine 
apertures  on  brackets.  What  tools  are  in  sight  are  neatly 
hung  up  on  the  wall.  The  conduit  is  not  buried  in  the 
floor,  ceiling  or  walls  as  it  should  be,  but  this  could  not 
be  avoided  as  the  walls  of  the  room  are  of  hollow  tile  and 
the  local  laws  will  not  permit  a  conduit  to  be  placed  inside 
of  that  kind  of  operating  room  wall.  It  is  true  that  a 
conduit  on  the  face  of  the  wall  serves  the  purpose  just  as 
well  from  an  electrical  standpoint  as  it  would  were  it 
buriedi  in  the  wall,  but  it  looks  bad  and  spoils  the  finish 
of  the  room.  There  is  a  wash  basin,  with  cold  and  hot 
water,  but  an  apparent  absence  of  seats  for  the  operators, 
and  that  I  cannot  agree  with. 

/  believe  the  operator  is  much  more  likely  to  remain  at  his 
machine,  where  he  belongs,  if  there  is  a  comfortable  seat  pro- 
vided, and  surely  he  will  do  as  good  or  better  work  when 
seated  at  his  machine  than  when  running  around  the  operating 
room,  letting  George  (the  motor)  project  the  picture. 

The  room  is  10  x  15  feet,  with  a  ceiling  10  feet  at  the 
walls  and  12  feet  in  the  center  where  there  is  a  36  x  40  inch 
vent  flue,  in  which  is  an  18-inch  G.  E.  exhaust  fan.  In  the 
rear  wall,  only  part  of  which  is  shown,  are  two  windows 


246 


MOTION    PICTURE    HANDBOOK 


FOR    MANAGERS    AND    OPERATORS 


247 


248  MOTION    PICTURE    HANDBOOK 

30  x  40  inches,  each  having  a  16-inch  fan  set  in  its  center. 
The  windows  open  on  a  10-foot  court,  and  are  metal  instead 
of  glass. 

Each  machine  is  connected  to  two  rheostats  in  multiple, 
and  it  will  be  noted  the  rheostats  are  placed  near  the  ceil- 
ing, where  they  should  be.  There  is  a  voltmeter  and  an 
ammeter,  but  these  two  instruments  are  poorly  located, 
as  the  operator,  when  standing  ,at  the  machine,  would  have 
to  turn  round  to  see  them,  and  that  is  not  good.  There 
are  three  projectors,  which  eliminate  all  possibility  of 


Figure  98. 

trouble  *  from  a  break-down.  The  observation  ports  are 
8x12  inches.  The  walls  are  of  tile  and  brick,  18  inches  thick, 
with  a  ceiling  of  steel  roofing  with  an  air  gap  of  3  inches 
above  and  then  metal  lath  plastered.  The  floor  is  of 
cement,  built  up  on  the  ground,  covered  with  battleship 
linoleum  one-fourth-inch  thick.  The  floor  of  the  operating 
room  is  only  3  feet  6  inches  above  the  main  floor  of  the 
theatre.  The  lens  ports  are  6  feet  8  inches  from  the  main 
floor,  which  places  the  lens  in  almost  perfect  line  with  the 
center  point  of  the  screen.  The  cabinet  next  to  the  sink 
contains  controls  for  the  heating  system,  the  center  one  the 
switches  for  the  theatre  lights,  and  the  third  the  fuse  board 


FOR    MANAGERS    AND    OPERATORS 


249 


for  the  operating  room.  There  are  two  sets  of  No.  6  wire 
running  to  each  machine,  each  set  connected  to  separate 
fuses.  The  machine  switch  of  the  two  outside  machines  is 
double-throw,  so  that  by  throwing  the  switch  over  a  new 
set  of  fuses  is  cut  in.  We  see  the  corner  opposite  the  sink 
in  Fig.  98.  The  bank  of  six  lamps  and  the  batteries  are 
the  business  end  of  the  safety  lighting  system  required  by 
Ohio  law.  It  automatically  lights  small,  low  voltage  lamps 
in  the  auditorium  if  anything  goes  wrong  with  the  main 


Figure  99. 

circuit,  thus  preventing  the  plunging  of  the  auditorium  into 
darkness. 

I  am  informed  that  the  card  index  shown  immediately 
under  the  cabinet  contains  more  than  two  thousand  ques- 
tions and  answers  on  operating  and  the  things  allied  thereto. 
The  typewriter  is  used  in  connection  with  the  card  index. 
Notice  the  extra  parts  neatly  arranged  on  the  wall;  the 
program  slate;  the  extra  reels  and  wire;  the  oil  cans  and 
the  electric  battery  flash  lamp. 

This  installation  is  the  work  of  Howard  W.  Codding, 
who,  by  the  way,  was  one  of  the  organizers  of  the  Cleve- 
land operators'  union.  Judging  from  these  pictures,  Brother 
Codding  is  a  thoroughly  capable,  enterprising  and  progres- 
sive operator,  and  one  not  merely  satisfied  to  be  able  to 


250  MOTION    PICTURE    HANDBOOK 

draw  his  Saturday  night's  pay,  giving  the  least  possible 
mental  and  physical  effort  in  return. 

Later:  I  am  informed  that  there  are  comfortable  chairs 
for  the  operators,  though  they  do  not  show  in  the  pictures. 

Fig.  99  shows  the  operating  room  of  the  Pathe  projec- 
tion room  at  the  American  headquarters  of  that  company. 

I  have  used  these  operating  room  illustrations  for  two 
reasons:  first,  they  are  excellent  of  their  kind,  and  I  believe 
will  serve  to  offer  suggestions  to  others  planning  similar 
installation;  second,  to  mildly  criticise  the  faults  shown, 
but  I  wish  it  understood  that  these  installations  are  never- 
theless good,  and  good  ones  to  copy,  too,  with  the  faults 
mentioned  eliminated. 

With  regard  to  the  projection  circuit,  when  it  cannot  be 
carried  under  the  floor  it  should  by  all  means  be  carried 
through  and  above  the  ceiling,  if  possible,  or  if  that  cannot 
be  done  then  along  the  surface  of  the  ceiling  to  a  point 
just  to  the  left  of  the  projector  lens  hole,  and  thence  down 
the  wall  and  back,  either  along  the  left  side  of  the  machine 
or  along  the  floor,  according  to  individual  preference,  to 
an  outlet  located  under  the  lamphouse.  Some  of  these 
various  methods  are  shown  in  the  illustrations.  There  is 
no  rule  which  can  be  made  to  apply  to  all  installations. 

As  a  rule  inspectors  require  that  all  switches,  except  those 
of  the  inclosed  type,  and  all  fuses  be  inclosed  in  a  metal 
cabinet,  and  it  undoubtedly  does  add  .an  element  of  safety, 
since  there  is  always  a  chance  of  something  inflammable 
falling  against  an  open  switchboard  and  causing  trouble,  or 
of  the  operator  himself  accidentally  coming  into  contact  with 
it  and  receiving  a  bad  shock  or  burn. 

With  modern  projectors  the  operating  switch  is  invariably 
a  part  of  the  machine,  and  located  under  or  beside  and 
below  the  lamphouse.  These  switches  must  be  of  the 
inclosed  type — inclosed  in  a  sheet  metal  casing. 

Double  Throw  Connection. — Two  projectors  should  never 
be  connected  through  a  double-throw  switch  with  the  supply 
attached  to  the  center  contacts,  so  that  it  is  necessary  to  ex- 
tinguish one  lamp  to  light  the  other',  except  in  cases  where 
current  is  taken  through  a  single  motor  generator  or  recti- 
fier of  insufficient  capacity  to  supply  both  lamps.  In  that 
event  it  is  well  to  make  that  sort  of  connection,  but,  on 
the  other  hand,  it  is  advisable  where  that  condition  prevails 
to  arrange  so  that  the  idle  lamp  may  be  operated  through 
a  rheostat  taking  current  directly  from  the  supply  lines 


FOR    MANAGERS    AND    OPERATORS 


251 


ahead     (on    the    street    side)     of    the    motor    generator    or 
rectifier. 

This  sort  of  connection,  shown  in  Fig.  100,  is  entirely 
practical  and  not  at  all  expensive  to  make.  In  practice  I 
think  the  change  from  rheostat  to  compensarc  could  be 
made  without  breaking  the  arc.  The  idle  lamp  would  be  lit 
up,  using  current  through  the  rheostat,  about  two  or  three 
minutes  before  the  reel  on  the  other  machine  was  ended 
and  at  the  changeover  the  operator  would  quickly  throw 


Figure  100. 

over  the  four-pole  switch  and  pull  the  machine  table  switch 
on  the   machine  which   had   finished  its   task. 

Except  under  the  circumstances  just  named  every  machine 
circuit  should  be  entirely  independent  of  every  other  circuit. 
Connect  every  projector  lamp  and  every  stereo  lamp  entirely 
independent  of  every  other  lamp  and  you  will  avoid  trouble 
and  annoyance. 

Polarity  Changer. — Where  the  supply  is  taken  from  a 
small  D.  C.  plant  it  sometimes  occurs  that  when  dynamos 
are  changed  the  polarity  changes,  which  requires  the  instant 
switching  of  your  own  wires  to  bring  the  positive  back  to 


252 


MOTION    PICTURE    HANDBOOK 


the  top  carbon.  This  may  quickly  be  accomplished  by  the 
installation  of  a  double-throw  double-pole  switch,  such  as 
is  seen  in  Fig.  101.  Throwing  this  switch  over  changes 
the  polarity  of  the  wires.  The  cross  wires  should  be  pro- 


Figure  101. 

tected  by  flexible  insulating  tubing  in  addition  to  their  own 
insulation. 

Fig.   102  is  a   diagram  of  a  combined  polarity  switch   and 
fuse   changer.     By   throwing   switch   A   a   new   set   of   fuses 


Figure  102. 

is  cut  in  and  by  throwing  switch  B   the  polarity  at  the  arc 
is  changed. 

Connecting  to  Two  Sources  of  Supply. — For  various  rea- 
sons it  is  frequently  desirable  to  make  connection  to  two 
separate  sources  of  electrical  supply.  One  may  have  one's 


FOR    MANAGERS    AND    OPERATORS 


253 


own  light  plant,  but  wish,  in  case  of  accident,  to  be  able  to 
instantly  connect  to  the  wires  of  the  city  plant.  This  may 
readily  be  done,  but  due  to  varying  conditions  details  may 
vary  widely  in  different  cases.  Suppose  we  have  a  house 
plant  delivering  direct  current  at  110  volts,  while  the  city 
plant  produces  A.  C.  at  110  volts;  both  systems  two-wire. 
The  problem  then  is  simple. 

Install  a  double-pole,  double-throw  switch,  as  per  Fig.  103. 
The  house  plant  being  D.  C.,  we  shall  not  need  nearly  so 
much  amperage  from  it  as  would  be  necessary  for  equal 
screen  illumination  with  the  city  plant,  A.  C.;  therefore,  we 
install  two  rheostats,  A  and  C,  the  lower  one,  A,  to  be  used 
with  a  D.  C.  house  plant.  B  is  a  double-pole  single-throw 


Figure  103. 


knife  switch  which  is  open  when  D.  C.  is  in  use,  so  as  to 
use  only  rheostat  A.  When  we  throw  over  to  the  A.  C, 
however,  we  close  switch  B,  thus  cutting  rheostat  C  in 
multiple  with  rheostat  A.  Rheostat  C  should  have  capacity 
sufficient  to  build  the  combined  amperage  of  the  two  up 
to  that  necessary  for  good  illumination  of  the  screen.  Sup- 
pose we  use  35  amperes  D.  C.  In  order  to  secure  anything 
like  the  same  curtain  brilliancy  rheostat  C  must  have  ca- 
pacity sufficient  to  deliver  25  amperes  which,  combined  with 
the  capacity  of  rheostat  A,  will  give  60  amperes  at  the  arc. 
But  we  must  remember  that,  owing  to  the  shorter  A.  C. 
arc,  hence  the  less  arc  resistance,  rheostat  A  will  deliver 
somewhat  more  current  on  A.  C.  than  it  will  on  D.  C.,  the 
voltage  of  the  supply  being  the  same  in  both  cases.  We 


254 


MOTION    PICTURE    HANDBOOK 


will  probably,  therefore,  be  not  far  out  of  the  way  if  we 
have  rheostat  C  of  capacity  to  deliver  20  amperes  at  the  arc. 
We  may,  however,  instead  of  this,  install  a  transformer 
(economizer,  inductor,  compensarc,  etc.),  in  place  of  rheostat 
C,  Fig.  103,  and  with  a  triple-pole  double-throw  switch,  wired 
as  per  Fig.  104,  cut  out  resistance  A,  Fig.  103,  substituting 
the  economizer  therefor.  Merely  throwing  the  switch  over 


Figure  104. 


would  then  change  from  rheostat  to  transformer,  and  vice 
versa,  though  the  transformer  would  be  "alive"  in  the  sense 
that  you  could  get  a  shock  from  it.  But  this  would  do  no 
harm.  If  you  wish  to  "kill"  the  transformer  entirely  when 


Figure  105. 

using  the  rheostat,  it  may  be  done  by  installing  a  S.  P.  S.  T. 
switch  at  X,  Fig.  104. 

Please  understand  there  are  many  other  switch  arrange- 
ments possible.  Such  things  may  be  done  in  many  ways. 
Those  suggested  merely  illustrate  two  possible  methods. 
Another  and  still  better  way  to  cut  the  two  rheostats  in 


FOR    MANAGERS    AND    OPERATORS  255 

multiple,  Fig.  105,  is  by  means  of  a  triple-pole,  double-throw 
switch. 

A  careful  tracing  out  of  the  connections  in  Fig.  105  will 
show  that  when  the  switch  is  thrown  to  the  A.  C.  supply 
side  the  two  rheostats  are  in  multiple,  while  when  the  D.  C. 
side  is  in  use  only  rheostat  1  is  working.  Should  the  supply 
voltage  be  higher  on  one  system  than  on  the  other,  a  higher 
voltage  rheostat  could  be  substituted  for  A,  Fig.  103,  and 
rheostat  C  be  made  of  such  capacity  that  it  will  bring  the 
amperage  up  to  normal  when  on  the  lower  voltage. 


Grounds 

ONE  of  the  most  puzzling  things  to  the  novice,  and  one 
not  too  well  understood  by  many  experienced  opera- 
tors, is  what  is  termed  a  "ground,"  meaning  a  con- 
tact with  some  current  carrying  material  by  means  of  which 
the  current  can  escape  from  one  wire  of  a  circuit  into  the 
ground  and  through  the  ground  to  some  point  where  a  wire 
of  opposite  polarity  attached  to  the  same  generator  has  con- 
tact with  the  ground,  or  is  "grounded."  Incidentally,  when 
a  conductor  of  current,  such,  for  instance,  as  the  metal  of 
a  lamphouse,  has  electrical  connection  with  either  side  of 
the  circuit,  that  side  of  the  circuit  is  said  to  be  "grounded 
to  the  lamphouse,"  e\en  though  the  lamphouse  itself  is  insu- 
lated from  the  opposite  polarity,  so  that  no  current  can 
flow.  This  is,  however,  not  a  ground  in  the  true  sense. 

The  neutral  of  all  Edison -three-wire  systems  is  grounded 
to  earth.  This  is  a  true  ground,  and  if  an  accidental  ground 
occurs  on  the  other  wires  of  the  system,  the  current  will 
return  to  the  dynamo  through  the  earth,  and  thus  form  a 
short  circuit,  blowing  the  fuses  protecting  the  circuit  on 
which  the  ground  occurs. 

And  now  right  here  let  me  make  it  clear  that  the  somezvhat 
common  belief  that  current  seeks  to  escape  from  the  wires 
into  the  ground  is  wrong,  except  ivhen  by  so  doing  it  can  find 
a  path  to  a  ivire  of  opposite  polarity  which  is  attached  to  the 
same  dynamo.  Let  me  also  emphasize  the  fact  that  the  cur- 
rent generated  by  one  dynamo  will  not  seek  the  opposite 
polarity  of  another  dynamo,  but  only  that  of  its  own  gen- 
erator. 

Electric  current  has  absolutely  no  affinity  whatever  for  any- 
thing under  the  sun  except  a  wire  of  opposite  polarity  attached 
to  the  same  generator. 


256 


MOTION    PICTURE    HANDBOOK 


If  the  positive  or  negative  wires  of  a  generator  carrying 
ten  thousand  Volts,  or  for  that  matter  fifty  thousand,  were 
thoroughly  and  completely  insulated  (a  condition  never 
found  in  actual  practice)  you  could  stand  with  your  bare 
feet  on  wet  ground  and  'handle  a  wire  carrying  the  full 
voltage  with  your  bare  hands  without  any  danger  whatever, 
but  if  you  attempted  to  do  this  and  the  wire  of  opposite 
polarity  be  grounded  at  any  point,  the  current  would  in- 
stantly leap  through  your  body  into  the  earth,  follow  the 
path  of  least  resistance  to  the  point  where  the  other  wire 
was  grounded,  and  enter  it;  or,  lest  we  become  confused, 
assuming  that  current  flows  from  positive  to  negative,  if  you 
held  the  negative  wire,  then  the  current  would  leave  the 


°\ 

X 

V 

.  (- 

A 

Figure  106. 

positive,  enter  the  ground,  pass  through  the  ground  to  your 
feet,  up  through  your  body  and  into  the  negative.  The 
effect,  insofar  as  shock  be  concerned,  would,  of  course, 
be  identical,  regardless  of  which  way  the  current  might 
flow.  I  emphasize  this  because  some  are  puzzled  by  the 
fact  that  when  they  touch  a  negative  wire  they  get  just  as 
heavy  a  shock  as  they  do  when  they  touch  the  positive. 

Examining  Fig.  106,  A  is  a  circuit  attached  to  dynamo 
G,  and  B  a  subsidiary  circuit  branching  from  it.  Now,  let 
us  assume  that  the  system  is  grounded  at  point  Z,  in  the 
lower  or  negative  carbon  arm,  and  at  point  X  on  the  posi- 
tive of  the  subsidiary  circuit.  In  this  case  the  current  would 
leave  the  positive  at  X,  travel  through  the  ground,  seeking 
the  path  of  least  resistance,  which  might  lead  it  through 
some  distance,  to  point  Z,  where  it  would  enter  the  carbon 


FOR   MANAGERS    AND    OPERATORS 


257 


arm.  You  will  observe  that  it  does  not  enter  circuit  C, 
attached  to  generator  Y,  although  the  negative  of  that 
dynamo  is  grounded,  let  us  assume,  at  T.  The  curves  in 
the  line  are  merely  designed  to  show  the  devious  path  the 
current  may  traverse  in  seeking  the  path  of  least  resistance. 

Again,  let  us  suppose  rheostat  E  to  be  grounded,  it  being 
on  the  true  positive  of  an  Edison  three-wire  system,  or 
the  positive  of  an  insulated  system,  and  that  a  ground  on 
the  neutral  or  the  negative  exists  at  O.  The  current  then 
leaves  your  rheostat,  passes  into  the  earth  and  follows  a 
water  main,  or  possibly  a  gas  main,  or  perhaps  the  earth 
itself  to  point  O,  where  it  finds  what  it  is  seeking,  viz.:  a 
point  at  which  it  can  get  into  the  negative  wire.. 

With  regard  to  the  three-wire  system  grounding,  it  is  a 
great  puzzle  to  many.  Let  me  say,  in  the  beginning,  that 
there  are  two  kinds  of  three-wire  systems,  viz:  the  Edison 
system,  in  which  the  neutral  is  always  thoroughly  grounded 
at  the  generator  and  at  other  points,  and  the  three-wire 
system  in  which  the  whole  system  is  insulated.  The  reason 
for  grounding  the  neutral  in  the  Edison  system  is  to  prevent 
any  possibility  of  the  conduit  in  buildings  being  charged  at 
220  volts,  or,  to  put  it  in  electrical  terms,  to  limit,  the  dif- 
ference of  potential  between  any  wire  and  the  conduit  sys- 
tem in  buildings  to  110  volts.  The  insulated  three-wire 
system  is,  so  far  as  the  writer  knows,  only  used  for  small 
plants. 


3 


Figure  107. 


With  the  Edison  three-wire  system  your  test  lamp  will 
not  show  a  light  from  ground  to  neutral,  and  if  your  neutral 
carbon  arm  should  be  grounded  there  will  be  no  effect, 
unless  the  rheostat  is  in  the  neutral  wire,  in  which  case  the 


258 


MOTION    PICTURE    HANDBOOK 


fuses  may  blow  when  the  arc  is  struck,  by  reason  of  the 
fact  that  the  striking  of  the  arc  completes  the  circuit  through 
the  ground,  as  indicated  in  Fig.  106,  thus  eliminating  a  por- 
tion or  all  of  the  rheostatic  resistance,  the  amount  elimi- 
nated depending  upon  how  heavy  the  ground  may  be. 

It  might  incidentally  be  mentioned  that,  theoretically  at 
least,  it  would  be  quite  possible  when  using  the  Edison 
three-wire  system  to  locate  the  rheostat  on  the  outside  wire, 
remove  the  insulation  from  the  carbon  arm  of  the  lamp  to 
which  the  neutral  is  attached,  disconnect  it  from  the  wire 
and  thoroughly  ground  the  carbon  arm,  whereupon  the  arc 
would  operate  the  same  as  though  it  was  connected  up  to 
the  system.  The  above  is  merely  cited  as  a  curiosity,  and 
not  because  it  is  really  a  practical  thing  to  do. 

Gounds  may  be  tested  for  with  a  test  lamp.  This  may  be 
a  single  lamp,  of  the  voltage  of  your  system,  to  which  two 
wires  of  convenient  length  are  connected,  or  when  using 
the  Edison  three-wire  system,  the  test  lamp  may  be  made  up 
as  per  Fig.  107.  The  lamp  combination  used  in  Fig.  107  is 
designed  to  be  used  on  either  110  or  220  volts. 


Figure  108. 

On  110  volts,  wires  A  and  C  only  should  be  used,  but  on 
220  use  wires  A  and  B,  the  lamps  being  110  volt  globes, 
preferably  of  low  candle  power,  though  standard  lamps  will 
do.  If  you  are  not  using  110  or  220  volts,  then  you  will,  of 


FOR    MANAGERS    AND    OPERATORS  259 

course,  use  lamps  of  whatever  voltage  your  system  may 
happen  to  be. 

It  is  highly  desirable  to  have  a  permanent,  known  ground 
in  the  operating  room,  and  this  may  best  be  established  by 
either  attaching  a  copper  wire,  No.  22  or  larger,  to  a  water 
pipe,  or  else  by  soldering  the  end  of  such  a  wire  to  a  copper 
plate  not  less  than  one  foot  square,  and  burying  the  plate, 
embedded  in  powdered  coke,  in  the  ground  deep  enough 
to  secure  its  contact  with  moist  earth.  Having  established 
the  ground  by  either  of  the  above  described  methods,  carry 
the  other  end  of  the  wire  through  the  wall  of  the  operating 
room  at  any  convenient  point  and  attach  a  binding  post  at 
its  end.  This  forms  a  permanent,  known  ground.  To  at- 
tach the  ground  wire  to  the  water  pipe  the  best  method  is, 
using  a  file  or  emery  cloth,  to  polish  the  pipe  perfectly 
clean  and  bright  for  one  or  two  inches  of  its  length,  and 
then,  first  having  stripped  the  insulation  from  four  or  five 
feet  of  the  end  of  the  wire,  and  scraped  the  wire  perfectly 
clean,  wrap  the  same  many  times  around  the  pipe  tightly, 
and  fasten  it  securely  in  place,  but  be  sure  that  the  wire  is 
held  tightly  to  the  pipe.  Having  finished  this,  we  will  pro- 
ceed to  attach  the  test  lamp  socket  firmly  to  the  wall,  in  any 
convenient  manner,  close  to  the  end  of  the  ground  wire,  and 
join  one  of  its  binding  posts  thereto  by  means  of  a  short 
piece  of  wire.  Now  cut  a  piece  of  insulated  wire  (braided 
lamp  cord  is  excellent  for  the  purpose)  long  enough  to  reach 
from  the  other  binding  post  of  the  test  lamp  to  any  point  in 
the  operating  room  where  you  are  likely  to  want  to  make  a 
test.  Attach  one  end  of  this  wire  to  the  other  test  lamp 
binding  post  and  you  will  then  be  in  a  position  to  make  a 
ground  test  instantly  at  any  time,  simply  by  touching  the 
lead  wire  from  the  lamp  to  the  object  you  desire  to  test,  the 
lead  wire  being,  of  course,  kept  coiled  up  on  the  wall  beside 
the  test  lamp  when  not  in  use,  all  of  which  is  shown  in 
Fig.  108. 

It  is  quite  possible  the  object  to  be  tested  may  be  grounded 
and  still  not  light  the  lamp,  by  the  reason  of  the  high  resist- 
ance of  the  ground  not  allowing  sufficient  current  to  pass  to 
heat  the  filament,  but  this  kind  of  ground  will  be  detected, 
nevertheless,  by  reason  of  the  fact  that  the  end  of  the  wire 
will  show  a  spark  when  the  contact  is  broken.  For  this 
reason  it  is  always  better,  when  possible,  to  test  in  a  mod- 
erately dark  room.  With  this  arrangement  the  operator  can 
test  his  aparatus  every  day  without  trouble  or  inconvenience. 


260 


MOTION    PICTURE    HANDBOOK 


However,  you  must  bear  in  mind  that  when  using  an  Edison 
three-wire  system  you  cannot  test  any  apparatus  connected 
only  to  the  neutral  wire  with  a  test  lamp,  because  they  are 
permanently  grounded  with  the  neutral.  In  testing  with  a 
dry  battery  it  is  not  necessary  to  use  a  bell;  just  connect  two 
wires  to  the  battery,  and  make  your  test.  If  there  Is  a 
ground  there  will  be  a  spark.  It  is  better,  however,  to  use 
two  or  more  batteries  connected  in  series. 

With  the  insulated  three-wire   system  the   test  lamp  acts 
the  same  as  with  the  two-wire  system. 


n 


Figure  109. 

Locating  a  grounded  coil  in  the  rheostat  is  a  deep,  dense 
mystery  to  many  operators,  but  it  really  is  a  very  simple 
matter.  Fig.  109  is  a  diagrammatic  representation  of  a  rheo- 
stat; A,  B,  C,  D,  etc.,  indicating  the  coils  or  grids,  coil  or 
grid  E  being  grounded  to  the  frame  at  X.  Assuming  that  we 
wish  to  test  this  rheostat  to  find  out  whether  or  not  it  is 
in  good  order,  using  a  magneto  or  bell  and  battery,  first 
touch  the  binding  posts  with  the  two  leads  from  the  bell 
and  battery,  or  magneto.  If  you  get  a  ring  it  indicates  that 
the  circuit  is  complete;  that  is  to  say,  no  cojl  js  broken  or 


FOR   MANAGERS   AND    OPERATORS  261 

disconnected.  Next  touch  one  binding  post  and  the  outer 
casing  or  frame  of  the  rheostat.  If  you  get  no  ring  then 
the  rheostat  may  be  considered  in  good  order,  except  for 
one  thing  which  cannot  be  located  with  a  bell  or  test  lamp, 
viz.,  two  coils  being  sagged  together  so  as  to  eliminate  a 
part  of  the  resistance  without  breaking  the  circuit. 

The  rheostat  may  be  tested  with  a  test  lamp  in  a  number 
of  different  ways.  First,  assuming  the  rheostat  to  rest  upon 
a  marble  slab,  or  other  insulating  material,  with  the  current 
on,  touch  your  test  lamp  to  the  frame  of  the  rheostat  and 
to  the  wire  of  opposite  polarity.  If  you  get  a  spark,  or  light, 
the  coils  or  grids  are  grounded  to  the  frame,  and  the  ground 
can  be  located  as  hereinafter  described.  Another  way  would 
be  to  disconnect  the  wire  leading  from  the  rheostat  to  the 
lamp  from  the  rheostat  binding  post  and,  with  the  switch 
closed,  touch  the  frame  of  the  rheostat  with  one  test  lamp 
lead  and  the  wire  which  has  just  been  disconnected  with 
the  other,  the  arc  lamp  carbons  being  "frozen,"  i.e.,  in  con- 
tact with  each  other.  If  you  get  a  light  or  a  spark  there 
is  a  ground;  if  not,  there  is  none.  Still  another  way,  again 
assuming  the  rheostat  to  rest  on  an  insulating  shelf,  discon- 
nect one  of  the  wires  from  the  rheostat  binding  post  and, 
with  the  carbons  of  the  lamp  frozen  and  the  switch  closed, 
touch  the  disconnected  wire  end  to  the  frame  of  the  rheo- 
stat. If  you  get  a  spark  there  is  a  ground. 

Now  suppose  you  have  applied  one  of  these  tests  and 
find  there  is  a  ground  in  the  rheostat,  indicating  that  one 
of  the  coils  is  electrically  connected  with  the  frame.  How 
are  you  going  to  locate  the  particular  coil  or  grid  at  fault? 
This  is  a  point  which  puzzles  so  many  operators,  yet  it  is 
as  simple  as  a,  b,  c,  when  you  come  to  examine  it  in  the 
light  of  common  sense.  Close  the  switch,  and,  if  you  are 
using  a  test  lamp,  attach  one  test  lamp  lead  to  one  of  the 
rheostat  binding  posts.  Now  attach  the  other  test  lamp  lead 
to  the  frame  of  the  rheostat,  and,  beginning  at  the  end  far- 
thest from  the  binding  post  the  test  lamp  lead  is  attached 
to,  disconnect  the  first  coil,  which  we  will  assume  to  be  coil 
A,  Fig.  109.  The  light  still  burns.  Disconnect  coils  B,  C, 
and  D  in  turn.  The  light  still  burns.  Disconnect  coil  E 
and  the  light  goes  out,  because  you  have  removed  the  ground. 
You  will,  therefore,  proceed  to  examine  coil  or  grid  E  and 
locate  the  trouble,  which  may  and  probably  will  be  due  to 
a  ground  through  the  insulation  of  the  connection  at  Z. 

Where  a  rheostat  consists  of  two  blanks  of  coils  or  grids 
considerable  labor  can  be  saved  by  disconnecting  one  side 


262  MOTION    PICTURE    HANDBOOK 

or  bank  from  the  other,  and  then  testing  each,  as  a  whole, 
to  find  out  which  half  the  ground  is  on.  It  is  then  only 
necessary  to  disconnect  the  individual  coils  on  the  defective 
side. 

It  is  always  advisable  that  the  projection  machine  lamp- 
house  and  mechanism  be  grounded  to  the  metal  of  the  opera- 
ting room,  and  the  whole  may,  or  may  not  be  thoroughly 
and  permanently  grounded  to  a  water  pipe.  The  reason  for 
grounding  the  projection  machine,  especially  if  it  be  an  all 
metal  one,  to  the  operating  room  metal  work,  lies  in  the  fact 
that  if  the  machine  be  insulated  from  the  metal  of  the 
operating  room  and  the  lamp  should  become  grounded  to  the 
metal  of  the  lamphouse  it  would  charge  the  whole  mechan- 
ism, and,  should  the  operator,  when  putting  a  reel  in  the 
magazine,  touch  both  the  magazine  and  the  metal  of  the 
operating  room  with  the  reel,  there  would  be  a  spark  which 
might  set  the  film  on  fire. 

There  is  no  real  necessity  for  grounding  the  metal  of  the 
operating  room;  it  may  or  may  not  be  done,  as  best  suits 
the  ideas  of  the  individual. 

Testing  for  ground  is,  after  all,  a  matter  of  plain,  horse 
sense,  and  anyone  can  do  it  if  he  understand  electrical  action. 

THE  PROJECTOR 

The  Lamp  House. — Of  late  projection  machine  manufac- 
turers have  awakened  to  the  importance  of  a  carefully  con- 
structed  lamphouse,  and  the  later  models  of  all  standard 
projectors  leave  very  little  to  be  desired  so  far  as  the  lamp- 
house  be  concerned.  In  the  early  days,  when  it  was  the 
exception  to  use  in  excess  of  25  amperes  for  projection,  and 
30  was  about  the  limit,  no  one  paid  much  attention  to  the 
lamphouse.  It  was  a  little,  contracted  affair,  built  of  russia 
iron,  single  thickness,  which  merely  served  to  confine  the 
light,  or  some  of  it,  and  hold  the  condensers — after  a  fashion. 

The  lamphouse  of  the  modern  projector  is,  however,  in 
some  instances,  a  double  walled  affair,  lined  on  the  inside 
with  insulating  material.  Its  proportions  are  imposing;  its 
ventilation  is  very  carefully  planned,  and  in  fact  the  whole 
outfit  is  excellent  and  complete,  and  probably  will  not  be 
very  largely  improved  in  the  future,  except  as  to  the  con- 
denser mount,  which  still  leaves  considerable  to  be  desired. 

The  ventilation  of  the  lamphouse  is  of  extreme  importance, 
particularly  where  high  amperage  is  used.  If  your  lamp- 
house  is  of  the  type  having  screens  over  the  ventholes,  either 
above  or  below,  it  is  very  important  indeed  that  these  screens 


FOR    MANAGERS    AND    OPERATORS  263 

be  kept  perfectly  clean,  since  if  the  screen,  either  above 
or  below,  clogs  up,  then  ventilation  is  impeded  and  an  ex- 
cessive heat  is  set  up  inside  the  lamphouse.  This  has  a 
double  effect.  First,  it  tends  to  overheat  the  condensers— to 
raise  them  to  an  unnecessarily  high  temperature,  which  very 
largely  increases  liability  to  condenser  breakage  through 
sudden  and  extreme  contraction  of  the  lens,  especially  when 
the  lamphouse  door  is  opened  to  trim  the  lamp  immediately 
after  finishing  a  reel. 

The  lower  the  temperature  in  the  lamphouse  is  kept  the  less 
zvill  be  the  likelihood  of  condenser  breakage. 

That  is  a  plain,  common  sense  proposition  everyone  ought 
readily  to  understand.  It  also  is  very  plain  that  the  more 
open  and  free  the  ventilation  of  the  lamphouse  is  the  lower 
will  be  the  temperature  of  its  interior. 

The  second  effect  of  lack  of  ventilation  is  that  by  increasing 
the  temperature  inside  the  lamphouse  the  lamphouse  itself 
radiates  more  heat,  thus  increasing  the  discomfort  of  the 
operator  in  warm  weather. 

The  core  of  the  carbons  contains  a  substance  known  as 
water-glass,  and  the  residue  of  water-glass  is  a  white  ash 
which  coats  the  interior  lamphouse  walls  and  very  quickly 
clogs  the  holes  in  the  screen  at  its  top.  Therefore  it  be- 
hooves the  operator  to  clean  the  top  screen  every  day.  It  is 
not  a  dirty  job  if  it  is  done  every  day,  but  if  you  try  to  clean 
it  when  it  has  not  been  cleaned  in  a  long  while  you  had 
better  take  the  entire  lamphouse  off  and  take  it  out  of  doors 
to  clean  it  or  you  certainly  will  have  a  nasty  mess  in  the 
operating  room. 

Best  Method  of  Ventilation. — The  best  and  most  feasible 
scheme  for  ventilation  is  one  recommended  by  the  Projec- 
tion Department  of  the  Moving  Picture  World  more  than 
three  years  ago.  It  consists  of  running  a  3  or  4  inch  metal 
pipe  from  the  top  of  the  lamphouse  to  the  open  air,  or  up 
into  the  operating  room  vent  flue.  This  is  now  provided  for 
in  the  Power,  Edison,  Simplex  and  Baird  lamphouses  of  late 
design  by  an  opening  left  for  that  purpose. 

The  idea  is  set  forth  in  Fig.  110.  This  pipe  carries  away 
much  of  the  heat  of  the  arc,  reduces  the  liability  to  condenser 
breakage  and  renders  the  position  of  the  operator  far  more 
pleasant  through  the  hot  summer  months.  It  has  the  hearty 
indorsement  and  approval  of  the  Projection  Department  of 
the  Moving  Picture  World  and  of  the  author  of  this  book. 


264 


MOTION    PICTURE   HANDBOOK 


/  would  recommend  its  installation  in  all  operating  rooms,  but 
don't  just  run  a  short  piece  of  pipe  up  a  foot  or  so  above  the 
lamphouse.  It  would  be  perfectly  safe  to  do  that,  but  it 
would  not  carry  the  heat  outside  the  room,  and,  more- 
over, would  not  be  approved  by  the  authorities  in  cities. 
Run  the  pipe  out  to  the  open  air  or  up  into  the  operating  room 
vent  flue.  If  this  is  done  it  need  not  be  capped  with  a  screen, 
because  in  any  event  it  will  not  be  less  than  5  or  6  feet  long, 
and  by  no  stretch  of  the  wildest  imagination  would  a  spark 
from  the  electric  arc  reach  such  a  distance  as  that.  If  it  is 
necessary  to  swing  the  lamphouse  over  to  the  stereopticon, 


Figure  110. 

that  can  be  readily  provided  for  by  putting  in  a  swing  joint 
or  a  slip  joint,  or  a  combined  swing  and  slip  joint.  Most  of 
the  leading  machine  manufacturers  have  already  made  pro- 
vision so  that  this  sort  of  vent  pipe  can  be  attached  to  their 
lamphouse.  Where  suc'h  provision  is  not  made  the  pipe  may 
be  attached  by  cutting  through  the  top  of  the  lamphouse  and 
attaching  it  thereto  with  a  suitable  flange. 

In  most  cities  the  authorities  require  that  the  back  of  the 
lamphouse  be  entirely  inclosed.  This  is  pure,  unadulterated 
nonsense,  but  nevertheless  when  it  is  the  law  it  must  be 
complied  with.  Where  the  law  does  not  require  its  closure, 


FOR   MANAGERS   AND    OPERATORS  265 

however,  I  recommend  that  the  entire  back  of  the  lamphouse 
be  left  open,  unless  such  a  pipe  as  already  described  is  in- 
stalled, in  which  case  there  will  be  ample  ventilation  without 
removing  the  back. 

Lack  of  ample  ventilation  in  the  lamphouse  causes  moving 
picture  theatre  managers  in  this  country  a  large  sum  in  con- 
denser breakage  every  day.  I  should  say  this  item  alone  would 
run  to  at  least  two  and  perhaps  as  much  as  five  hundred  dollars 
a  day,  in  the  United  States  alone,  meaning  that  that  amount  of 
condensing  lenses  are  broken  that  would  not  be  broken  if  the 
lamphouse  had  ample  ventilation. 

Keep  Your  Lamphouse  Clean. — The  careful,  painstaking, 
competent  operator  will  keep  his  lamphouse  clean.  It  does 
not  look  well  to  find  a  half  inch  of  carbon  dust,  dirt  and 
pieces  of  broken  carbons  lying  on  the  floor  of  the  lamp- 
house.  It  does  not  give  one  a  good  impression  of  the  man 
in  charge.  It  is  not  the  workmanlike  way  of  doing  things. 

The  rods  upon  which  the  lamphouse  slides,  if  it  slides  over 
to  the  stereopticon,  should  be  kept  lubricated.  When  your 
lamp  has  the  desired  angle,  if  the  lower  carbon  jaw  comes 
into  contact  with  the  front  wall  of  the  lamphouse  you  should 
line  the  front  wall  at  that  point  with  one-eighth  inch  as- 
bestos millboard,  which  may  be  fastened  to  the  wall  by 
punching  four  screw  holes  and  attaching  the  board  with 
small,  short  stove  bolts.  If  your  lamphouse  is  of  the  old, 
unlined  type  it  is  also  an  excellent  plan  to  rivet  one-eighth 
inch  asbestos  millboard  to  the  left  hand  wall,  or  door,  op- 
posite the  binding  posts  of  the  lamp.  Many  annoying  grounds 
are  caused  by  a  stray  strand  of  the  asbestos-covered  lamp 
leads  protruding  and  making  electrical  contact  with  the  lamp- 
house. 

Arc  Projector. — Modern  lamphouses  are  provided  with  a 
properly  located  arc  observation  window  of  ample  dimen- 
sions, fitted  with  glass  of  a  color  combination  enabling  the 
operator  to  look  directly  at  the  arc  without  the  least  eye- 
strain. 

Many  operators,  however,  prefer  to  project  a  picture  of 
the  arc  on  a  white  screen  pinned  to  the  operating  room  wall. 
This  is  very  easily  done,  as  follows:  With  a  drill  or  punch 
not  exceeding  one-thirty-second  of  an  inch  in  diameter,  make 
a  hole  in  the  left  hand  wall,  or  door  of  the  lamphouse  exactly 
opposite  the  arc  when  it  is  in  proper  position.  Through  this 
hole  a  picture  of  the  arc  will  be  projected  to  any  white  sur- 
face held  a  short  distance  away,  but  the  image  will  be  upside 


266 


MOTION    PICTURE    HANDBOOK 


down.  The  picture  may  be  improved  by  placing  in  front  of 
the  hole  a  small  piece  of  a  broken  condensing  lens,  or  any 
small  lens  you  may  happen  to  have;  an  old  spectacle  lens 
will  often  serve.  It  is  also  possible  to  project  a  front  view 
of  the  arc  on  the  front  of  the  upper  magazine  of  the  pro- 
jector by  punching  a  small  hole  in  the  front  wall  of  the 


ELBERT   HOLDER 

Figure  111. 


lamphouse  just  above 
the  condenser  casing. 
Don't  have  the  hole 
too  large,  however, 
or  the  image  will 
not  be  sharp. 

Condenser  Holder. — 

It  is  only  of  late  that 
any  particular  atten- 
tion has  been  paid  to 
the  condenser  holder, 
but  several  holders 
have  now  been 
evolved,  the  intelli- 
gent use  of  which 


very    largely    eliminates    condenser     breakage. 

Condensers  break  because  one  part  of  the  lens  is  thin  and 
another  part  is  quite  thick.  Therefore  when  the  lens  is  sub- 
jected to  heat,  the  edge,  or  thin  part,  heats  up  very  rapidly 
as  compared  to  the  thicker  center.  Hence  the  edge  of  the 
lens  expands  and  contracts  much  more  rapidly  than  its 
center. 


FOR    MANAGERS    AND    OPERATORS 


267 


The  theory  of  these  improved  condenser  holders  is  that  by 
providing  a  heavy  band  of  metal  at  the  edge  of  the  lens 
there  will  be  a  retarding  effect  in  the  metal  which  will  hold 
down  the  temperature  of  the  edge  of  the  lens  when  it  is 
heating  up,  and  hold  up  its  temperature  when  it  is  cooling 
off,  so  that  the  center  and  edge  of  the  lens  will  cool  down 
approximately  at  the  same  speed,  and  thus  expansion  and 
contraction  will  be  fairly  equal  and  breakage  very  nearly 
eliminated.  The  theory  is  correct,  as  has  been  proven  in  hun- 
dreds of  instances  where  these  holders  have  been  installed. 

In  Fig.  Ill  we  see  four  styles  of  the  Elbert  holder  illus- 
trated. I  think  the 
idea  is  fairly  well  con- 
veyed by  the  pictures. 
The  lens  is  held  in 
place  by  spring  steel 
ring,  marked  X  in  the 
illustration.  The  El- 
bert holder  may  be 
used  for  both  the  front 
and  back  lens,  and  in 
fact  as  made  for  the 
Simplex  and  Motio- 
graph  it  does  ,hold  both 
the  front  and  back 
lenses.  The  Power  and 
Edison  'holder  is  made 
for  one  lens  only,  but  a 
pair  may  be  secured,  if  FREDDY  HOLDER 

desired,    so   as    to  hold  Figure  112. 

both    lenses. 

In  Fig.  112  is  shown  the  Preddy  holder,  also  an  excellent 
and  very  efficient  device  for  holding  the  rear  lens  of  the  con- 
denser. It  is  not,  however,  designed  to  hold  the  front  lens. 
Fig.  113  shows  the  method  of  its  installation  and  the  details 
of  its  construction.  It  is  made  of  cast  metal. 

No  doubt  machine  manufacturers  will  themselves  add  this 
feature  to  their  projectors  in  the  near  future.  In  fact  some 
of  them  have  already  done  so,  in  a  limited  way.  /  would 
strongly  advise  all  theatre  managers  to  have  their  lamphouscs 
equipped  with  one  of  these  devices,  particularly  if  they  are  using 
high  amperage.  To  those  troubled  with  condenser  breakage 
these  holders  zvill  save  their  cost  in  a  very  short  time.  Both' 
the  Preddy  and  Elbert  mounts  are  excellent  and  easy  to  install. 


268 


MOTION    PICTURE    HANDBOOK 


In  ordering  give  the  kind  and  model  of  your  projector.    Don't 

forget  that  part,  for  it  is  very  necessary. 
The  Lamp. — Light  is  the  very  foundation  of  projection,  and 

the  lamp  is  a  most  important  factor  in  the  production  of  good 

light.  In  fact,  the  production  of  the  best  possible  projection 
light  is  entirely  out  of  the  question 
where  a  poor  lamp  is  employed,  or  a 
lamp  that  is  dry,  loose  and  "wobbly," 
or  so  tight  in  its  joints,  or  so  dry, 
that  you  can  scarcely  move  its 
adjustment  wheels. 

In  the  past  two  years  there  has 
been  an  enormous  improvement  in 
the  design  of  projector  lamps;  in 
fact  it  is  only  within  that  time  that 
we  have  had  anything  like  an  efficient 
lamp.  The  manager  who  is  compel- 
ling his  operator  to  use  an  old  anti- 
quated type  of  lamp  is  doing  a  very, 
very  foolish  thing.  He  is  "saving  at 
the  spigot  and  losing  at  the  bung- 


Figure  113. 
hole."     He  is  injuring  the  results  on  his  screen  every  hour  he 


runs,  merely  to  save  a  few  dollars  in  the  purchase  price  of  a 
good  lamp. 

Many  an  operator  is  producing  poor  results  on  the  screen 
for  no  other  reason  than  (a)  he  has  an  old  out-of-date  lamp, 
not  having  the  proper  adjustments;  (b)  his  lamp  is  not 
properly  lubricated;  (c)  it  has  too  much  lost  motion  and 
shakiness;  (d)  his  lamp  is  too  tight  or  too  dry  to  allow  of 
his  making  proper  adjustments  of  the  arc;  (e)  its  carbon 
jaws  are  rough  and  dirty,  thus  preventing  good  contact  be- 
tween the  carbon  and  metal. 

It  matters  not  how  excellent  the  lamp  itself  may  be,  unless  it 
be  kept  in  proper  condition  and  properly  lubricated  it  cannot  be 
handled  properly  and,  therefore,  the  operator  cannot  make  the 
fine  adjustments  of  his  arc  which  are  absolutely  necessary  to 
good  projection. 

The  lamp  should  be  taken  apart  at  stated  intervals  and  thor- 
oughly lubricated  with  powdered  graphite.  It  is  of  little  use  to 
lubricate  the  lamp  with  grease  or  oil,  since  it  is  quickly  burned 
off  or  dried  by  the  heat,  besides  making  a  smudge  inside  the 
lamphouse  which  is  likely  to  cloud  the  lenses. 

Managers  should  in  all  cases  provide  plenty  of  good,  powdered 
graphitet  and  compel,  if  necessary,  their  operators  to  use  it  regu- 
larly on  the  lamps. 


FOR   MANAGERS   AND   OPERATORS  269 

Seventy-five  cents  will  get  a  can  large  enough  to  last  for 
a  year  of  more,  unless  it  be  wasted.  By  all  means  get  a  can 
at  once  unless  you  already  'have  it.  Powdered  graphite  may 
be  had  of  up-to-date  dealers.  If  you  fail  to  get  it  elsewhere 
it  may  be  had  of  the  Picture  Theatre  Equipment  Company, 
19  West  Twenty-third  street,  New  York — 20  cents,  by  parcel 
post.  This  company  has  it  both  dry  and  in  a  paste  form — • 
both  good.  Say  which  you  want  when  ordering. 

Operators  should  make  it  a  practice  to  take  their  lamp 
entirely  apart,  except  the  insulated  joints,  which  should  never 
be  disturbed,  once  a  week  if  they  are  running  a  twelve-hour 
show  and  using  heavy  amperage,  or  say  once  in  two  weeks 
if  the  running  time  does  not  average  more  than  five  hours  a 
day.  Take  out  all  the  screws,  dip  them  all  in  oil,  wipe  them 
off  clean  and  dip  them  in  a  box  of  graphite;  also  smear  all 
the  moving  parts  with  oil,  wipe  the  oil  off  and  rub  the  parts  in 
graphite;  the  oil  is  merely  to  make  the  graphite  stick.  There- 
fore all  surplus  oil  should  be  wiped  off  clean.  Don't  wipe  the 
parts  off  after  dipping  them  in  graphite.  Just  shake  the 
graphite  off  and  put  the  parts  back.  The  more  graphite 
adhering  to  them  the  better.  If  you  have  never  done  this 
you  will  be  astonished  at  what  a  difference  it  will  make  in 
the  handling  of  your  lamp  and  your  arc.  You  will  be  sur- 
prised at  how  much  better  you  can  gauge  your  light. 

Make  it  your  practice  to  take  out  the  carbon  clamp  screws 
every  day  before  starting  the  run,  and  lubricate  them  with 
graphite  as  before  set  forth. 

Do  this  and  you  won't  need  to  twist  them  up  with  a  plier; 
in  fact,  if  you  have  been  using  unlubricated  clamp  screws  you 
will  most  likely  crush  the  first  carbon  or  two  you  put  in. 

On  Pages  270,  271,  and  272  will  be  found  illustrations  of  the 
lamps  of  the  various  leading  projection  machines.  These 
are  given  in  order  that  the  operator  may  examine  the  gen- 
eral make-up  and  decide  for  himself  which  is  best.  To  this 
end  certain  letters  have  been  incorporated. 

(a)  Being  the  carbon  feed  handle;  (b)  the  handle  with 
which  the  lamp,  as  a  whole,  is  raised  up  or  down;  (c)  the 
handle  by  means  of  which  the  lamp  is  pulled  back  or  shoved 
ahead;  (d)  the  handle  by  means  of  which  the  whole  lamp 
is  swung  from  side  to  side;  (e)  the  handle  by  means  of  which 
the  upper  or  lower  carbon  is  swung  to  one  side  in  order  to 
accomplish  the  side-lining  of  the  carbons:  (f)  the  handle 
by  means  of  which  the  upper  or  lower  carbon  is  shoved 
ahead  or  pulled  back  in  order  to  govern  the  formation  of 
the  crater;  (g)  the  carbon  clamp  screws;  (<h)  the  insulation; 


270 


MOTION    PICTURE    HANDBOOK 


POWER'S 


(i)   the  means  by  which  the  carbon  arms  may  be  tilted  or 
angled;   (j)  the  hooks  to  hold  the  cables;  (k)  the  means  by 

which   the  whole   lamp 
is   angled. 

It  will  be  noted  that 
these  lamps  are  far 
more  substantial  than 
the  older  types.  They 
accommodate  12-inch 
carbons  above  and  6- 
^^^  inch  below.  They  are, 

t"       * '  JHSfik  without  exception,  well 

k      .      made  mechanically,  and 
..,;«4|JHV  •  have  all  the   necessary 

adjustments  to  enable 
the  operator  to  force 
his  arc  into  any  desired 
position.  The  old 
nuisance  of  weak  car- 
bon clamps  has  been 
done  away  with.  It  is 
rare  indeed  to  hear  of 
an  operator  breaking  a 
carbon  clamp  on  the 
newer  type  of  lamp. 
The  small  rack  bars 
have  given  place  to 
bars  of  generous  di- 
mensions, and,  in  fact, 
the  modern  lamp  leaves 
very  little  to  be  desired. 
It  is  extremely  im- 
portant that  the  inside 
of  the  carbon  clamps 
of  your  lamp  be  thor- 
oughly scraped  out  once 
a  week;  oftener  if  high 
amperage  is  used. 

Through  continued 
use  the  inside  of  the 
carbon  clamp  gradually 
becomes  rough,  pitted 


EDISON  SUPER 

Figure  114A. 

and  dirty.     If  left  un- 

cleaned  it  is  but  a  question  of  time  when  it  will  be  practically 
impossible  to  secure  good  contact  between  the  carbon  and  the 


FOR    MANAGERS    AND    OPERATORS 


271 


metal.  The  proximity  of  the  arc  operates  to  create  high 
temperature  in  both  the  metal  and  carbon  and  when  you  add 
to  this  the  heating  effect  of  poor  contact  the  result  is  very 
bad  indeed.  Needling  of 
the  carbons  also  may  be 
often  traced  to  this 
cause.  The  result  of 
this  kind  of  treatment  of 
the  carbon  arm,  if  long 
continued,  is  permanent- 
ly to  raise  its  resistance. 
The  moral  is,  keep  your 
carbon  contacts  perfectly 
clean,  not  sometimes,  but 
always.  No.  y*  emery 
cloth  wrapped  around  a 
small  file  makes  an  ex- 
cellent cleaning  tool. 


Asbestos  Wire  Lamp 
Leads.  —  The  asbestos 
wire  lamp  leads  should 
be  attached  to  the  car- 
bon arm  by  means  of 
a  wire  terminal  similar 
to  those  shown  in  Fig. 
29,  Page  87.  See  Page 
50  and  Page  233  for 
further  important  mat- 
ter on  the  subject  of 
lamp  leads. 

Be  sure  that  your 
lamp  wire  contacts  are 
kept  perfectly  clean. 
They  should  be  well 
polished  at  least  once 
every  week.  Metal 
oxidizes  under  the  ac- 
tion of  heat,  and  the 
scale  thus  formed, 
while  very  thin,  has 


SIMPLEX 


MOTIOGRAPH 

Figure  114B. 


high  resistance.  Due  to  this  fact  it  is  difficult  to  maintain  good 
electrical  contact  at  these  connections.  The  scale  may  be  al- 
most invisible,  but  it  is  likely  to  be  there  just  the  same, 
particularly  if  a  copper  wire-terminal  is  used. 


272 


MOTION    PICTURE    HANDBOOK 


AMERICAN  STANDARD 


Lamp  Insulation. — 
The  insulation  between 
the  carbon  arms  and 
the  body  of  the  lamp 
must,  of  course,  be  per- 
fect. A  ground  is  often 
formed  through  carbon 
dust  settling  on  the 
lower  carbon  arm  and 
forming  a  bridge  across 
the  insulation.  This  sort 
or  ground  would  not 
carry  much  current,  but 
it  is  likely  to  give  the 
operator  a  good,  lively 
shock  just  the  same,  if 
the  lamphouse  is  insu- 
lated and  he  is  grounded. 
If,  on  the  other  hand, 
the  lamphouse  is  ground- 
ed there  may  be  a  con- 


BAIRD 

Figure  114C 


FOR   MANAGERS   AND    OPERATORS  273 

stant  though  slight  loss  of  current.     The  moral  is,  keep  the 
dust  brushed  off  the  top  of  your  lower  carbon  arm. 

The  insulation  of  the  lower  carbon  arm  should  project 
above  the  surface  of  the  metal  at  least  one-eighth  of  an  inc'h. 
If  it  does  not,  loosen  the  joint  and  insert  a  piece  of  mica, 
allowing  it  to  do  so. 

Lamp  Adjustments. — The  modern  lamp  has  the  following 
adjustments,  all  capable  of  being  made  by  means  of  adjust- 
ment wheels  outside  the  lamphouse.  (a)  The  whole  lamp  up 
and  down;  (b)  the  whole  lamp  backward  and  forward;  (c)  the 
arc  itself  sidewise;  (d)  movement  of  rack  bars  to  feed  the 
arc;  (e)  side  movement  of  upper  or  lower  carbon  independent 
of  its  mate;  (f)  movement  backward  or  forward  of  the  upper 
or  lower  carbon  independent  of  its  mate.  These  independent 
carbon  movements,  e  and  f,  are  of  much  importance,  since 
only  by  their  use  can  the  crater  properly  be  handled  and 
compelled  to  form  in  the  proper  position.  (See  "Setting  the 
Carbons,"  Page  290.) 

The  backward  and  forward  movement  of  the  whole  lamp 
should  be  accomplished  by  means  of  a  very  coarse  screw  or 
its  equivalent,  since  it  is  foolish  to  be  compelled  to  give  the 
adjustment  wheel  half  a  dozen  turns  in  order  to  move  the 
lamp  a  quarter  of  an  inch. 

Angle  of  the  Lamp. — The  angle  at  which  the  lamp  should 
be  set  is  varied  somewhat  with  the  kind  of  current  and 
amperage.  For  direct  current  it  is  sufficient  to  say  that  the 
angle  should  be  as  much  as  it  is  possible  to  give  without 
causing  the  lower  carbon  tip  to  interfere  in  the  light.  (See 
"Carbon  Setting,"  Page  290.)  With  A.  C.  the  same  thing  is 
true,  but  one  has  to  use  considerable  more  care  when  deal- 
ing with  A.  C.  unless  the  amperage  be  above  60,  since  the 
crater  is  very  small. 

MOTOR  DRIVEN  MACHINES 

The  motor  driven  machine  is  a  fixture.  I  believe  it  fairly 
may  be  said  that  from  SO  to  75  per  cent  of  the  present  output 
of  the  projector  factories  are  equipped  with  motor  drives, 
and  at  least  one  manufacturer  equips  his  entire  product  thus. 

The  motor  driven  machine  is  an  unquestioned  blessing  to 
the  operator,  though  unfortunately  it  is  a  blessing  which 
may  very  easily  be  and  all  too  frequently  is  abused.  The 
author  has  long  since  taken  the  position  that  there  is  only 
one  proper  place  for  the  operator  while  the  picture  is  being 
projected,  and  that  is  right .  beside  his  machine,  with  his 


274  MOTION    PICTURE    HANDBOOK 

eyes  on  the  screen  every  instant  of  the  time.  With  the  hand 
driven  machine  he  is  compelled  to  stay  there,  and  that  is  the 
chief  advantage  urged  for  the  hand  drive.  However,  the 
driving  of  the  projector  by  hand  involves  a  very  distinct 
hardship  for  the  operator,  particularly  where  there  is  only  one 
employed.  It  means  that  for  from  three  to  eight  hours,  or 
even  longer,  he  is  compelled  to  turn  a  crank  continuously, 
and  this  task  is  made  none  the  easier  by  the  knowledge  that 
with  a  comparatively  nominal  first  cost  outlay  and  slight 
expense  thereafter  all  this  drudgery  could  be  performed  by 
a  motor. 

By  the  adoption  of  an  ordinance  requiring  that  the  motor 
circuit  be  controlled  by  a  switch  held  normally  open  by  a 
spring  (the  Massachusetts  law)  and  making  the  penalty  for 
holding  the  switch  closed  by  anything  except  the  operator's 
hand  punishable  by  revocation  of  the  theatre  license  for  two 
days  for  first  offense  and  ten  days  for  each  subsequent 
offense,  the  operator  may  be  effectively  located  at  the  pro- 
jection machine,  where  he  belongs. 

There  is  another  objection  to  the  motor,  that  is,  as  a  gen- 
eral proposition  the  speed  of  a  motor  driven  projector  can 
not  or  at  least  will  not  be  regulated  to  suit  the  action  in  the 
picture  as  closely  as  it  can  and  probably  will  be  where  a 
projector  is  hand  driven.  This,  however,  is  not  or  at  least 
would  not  be  a  serious  objection  if  some  scheme  be  devised 
to  keep  the  operator  at  the  machine,  where  he  belongs, 
because  with  the  more  up  to  date  motor  driven  projectors  it 
is  possible  to  change  the  speed  quickly,  and  with  a  fair 
degree  of  accuracy. 

There  are  a  number  of  types  of  motor  drives.  Almost  every 
machine  has  a  speed  regulating  device  of  its  own,  and  of 
course  each  manufacturer  claims  his  to  be  the  best.  They 
are  all  excellent  devices  of  their  kind,  and  of  course  the 
particular  one  put  out  by  each  machine  manufacturer  is 
especially  designed  and  adapted  for  use  on  the  machine 
made  by  that  manufacturer,  and  will  probably  give  better 
satisfaction  on  those  machines  than  will  any  other.  The 
mechanical  construction  of  these  various  drives  are  shown 
under  the  head  of  "Mechanisms." 

In  addition  to  this,  however,  there  are  a  number  of  motor 
drives  made  by  individual  manufacturers  for  use  on  old 
style  projectors  or  on  the  newer  projectors  which  are  not 
equipped  with  a  regular  motor  drive.  Two  of  these  which 
are  excellent,  and  can  be  recommended  by  the  author,  are 
the  John  D.  Elbert  Friction  Speed  Controller  and  the  Freddy 


FOR    MANAGERS    AND    OPERATORS 


275 


Speed  Controller,  both  of  which  are   moderate  in  price  and 
give  very  satisfactory  service. 

Elbert  Speed  Controller. — Fig.  115  is  an  illustration  of  the 
Elbert  Speed  Controller.  The  action  of  this  device  is  very 
simple,  and  it  readily  may  be  applied  to  any  make  of  ma- 
chine; also  it  may  be  operated  in  conjunction  with  any  style 
of  either  A.  C.  or  D.  C.  motor.  In  Fig.  115,  M  is  a  cast  iron 
disc  4l/2  inch  diameter,  rigidly  attached  to  the  same  shaft 
carrying  two-speed  pulley  A;  G  is  an  iron  disc,  or  plate, 
between  which  and  a  smaller  one  on  the  opposite  side  is 
clamped  friction  material  H,  which  impinges  upon  iron  disc 
M.  Wheel  G  is  rigidly  attached  to  shaft  E,  which,  together 
with  shaft  K,  forms  a  carriage  which  slides  endwise  through 
standards  J  and  L,  the 
end  motion  being  con- 
trolled by  regulating 
wheel  C,  which  op- 
erates screw  F,  thus 
moving  rods  E  and  K, 
wheel  G  and  pulley  B 
endwise.  The  action 
of  this  is  to  alter  the 
distance  of  wheel  G 
from  the  center  of 
wheel  M,  and  no  mat- 
ter whether  the  motor 
be  attached  to  pulley 
B  and  the  projection 


Figure  115. 


machine  to  pulley  A,  or  vice  versa,  any  alteration  of  the 
distance  of  wheel  G  from  the  center  of  disc  M  will,  of 
course,  alter  the  speed  of  the  projector.  It  will  thus  be 
seen  that  this  adjustment  in  conjunction  with  two-speed 
pulley  A  will  make  possible  the  graduation  of  the  speed 
of  the  projector  to  any  desired  value.  The  amount  of 
friction  between  wheel  G  and  disc  M  is  controlled  by 
spring  D,  and  the  end  thrust  thus  set  up  is  carried  by  ball 
bearing  N.  The  amount  of  friction  provided  by  spring  N 
is  adjustable,  and  should  be  only  sufficient  to  prevent  slip- 
page between  wheel  G  and  disc  N,  since  any  excess  would 
cause  the  motor  to  consume  unnecessary  power;  also  it 
would  cause  unnecessary  wear  on  the  parts.  This  device  is 
compact,  and  is  provided  with  nickled  compression  grease 
cups.  Its  price  is  $15,  and  may  be  shipped  parcel  post. 
Pulley  B,  to  which  the  machine  is  presumed  to  be  belted, 


276 


MOTION  PICTURE  HANDBOOK 


does  not  move  endwise  with  shaft  E,  but  by  a  very  simple  ar- 
rangement remains  stationary,  although  rigidly  attached  to 
the  shaft  so  far  as  the  driving  power  be  concerned.  The 
position  of  pulley  B  and  governing  wheel  C  and  screw  F 
are  interchangeable,  that  is  to  say,  these  parts  may  be  made 
to  change  places,  so  that  governing  wheel  C  can  be  at  either 
side  of  the  device,  as  is  most  convenient  to  the  operator. 
On  many  machines  the  device  may  be  conveniently  placed  on 
a  baseboard,  or  stand,  between  the  lamphouse  and  mechan- 
ism, with  the  motor  underneath,  but  the  position  will  vary 
with  local  conditions. 

Freddy  Speed  Controller. — Another  excellent  device  is  the 
Freddy  Speed  Controller,  illustrated  in  Fig.  116,  in  which 
the  parts  of  the  controller  are  shown  very  plainly.  It  may 

be  used  with  any  make 
of  projector  or  with 
any  kind  of  A.  C.  or 
D.  C.  motor.  Six  is  a 
disc  wheel,  carrying 
cone  pulley  3,  to  which 
the  projector  is  belted. 
Friction  Wheel  1  car- 
ries a  cone  pulley  to 
which  the  motor  is 
belted.  Friction  wheel 
1  is  attached  rigidly  to 
shaft  7,  wLich  is  moved 
endwise  by  handle  6. 
This  endwise  move- 
ment alters  the  point 
of  contact  between 
friction  wheel  1  and 
disc  wheel  6  with  rela- 
tion to  the  center  of  the  latter,  and  as  will  be  readily  seen  any 
change  in  this  respect  will  instantly  alter  the  speed  of  disc 
wheel  6  and  cone  pulley  3,  to  which  the  projector  is  belted. 
This  feature,  taken  in  conjunction  with  cone  pulley  3  and 
the  cone  pulley  carried  by  friction  wheel  1,  provides  a  very 
wide  and  finely  graduated  range  of  speed  for  the  projector. 
The  amount  of  friction  between  wheel  1  and  disc  6  is  de- 
termined by  coil  spring  5,  and  the  compression  of  this  spring 
may  be  readily  altered  by  moving  the  set  collar  at  its  end. 
The  end  thrust  thus  set  up  is  carried  by  ball  bearing  4. 
In  Fig.  117  the  method  of  attachment  is  illustrated.  It  is 


Figure  116. 


FOR    MANAGERS   AND    OPERATORS 


277 


important  that  the  motor  be  placed  not  less  than  18  inches  from 
a  cone  pulley  1,  Fig.  116.  The  bottom  lever  6  is  carried  by  a 
small  bolt  or  screw.  If  the  lever  shows  a  tendency  to  work 
either  way  of  its  own  account  tighten  this  bolt  or  screw. 
This  controller  costs  $12.50.  It  may  be  shipped  parcel  post. 

Multiple  Clutch  Controller.— J.  Claude  Re  Ville,  Florence, 
S.  C.,  also  makes  a  multiple  clutch  controller,  illustrated  in 
two  forms  in  Fig.  118.  This  is  a  line  shaft  scheme  by  means 
of  which  one  motor  drives  two  machines.  The  drawings,  I 
think,  explain  themselves.  Either  style  of  these  clutches  is 
claimed  to  be  an  improvement  over  using  two  motors,  be- 
cause of  the  perfect  control  obtained  over  either  machine  while 
seated  at  the  other.  These  clutches  are  made  and  sold,  so 
Brother  Re  Ville  says,  at  about  one-third  the  price  of  a 
good  motor,  and  they  are  guaranteed  by  their  makers  to 
give  satisfaction. 

I  do  not  myself  think 
very  much  of  the  up- 
per one,  because  it 
seems  to  me  that  either 
the  belt  would  have  to 
slip  or  the  machine 
start  with  a  jerk.  The 
lower  cone  clutch, 
however,  ought  to 
work  perfectly. 

A  fairly  good  speed 
controller  may  be  con- 
structed as  per  the  idea 
illustrated  in  Fig.  119. 
This  device  can  be 
made  efficient,  but  the 

cones  must  not  have  too  steep  a  pitch,  and  the  shafts  must 
be  in  good  alignment  or  the  belt  won't  run  right.  In  fact 
this  cone  idea  is  perhaps  the  simplest  and  best  of  any 
home-made  speed  controller  I  have  examined.  It  is  cheap, 
efficient,  and  fairly  durable.  I  would,  however,  as  a  general 
proposition,  advise  operators  and  managers  to  purchase  the 
regular  motor  drive  attachment  put  out  by  the  manufac- 
turers of  their  machines. 

In  designing  a  home-made  drive  it  should  be  remembered 
that  crank  speed  should  have  a  variation  of  about  45  to  70. 
/  would  caution  operators  against  belting  a  motor  to  the  fly 
wheel  of  their  projector.  The  fly  wheel  of  a  projector  is 


Figure  117. 


278 


MOTION    PICTURE    HANDBOOK 


mounted  on  the  shaft  carrying  the  cam.  It  is  a  high  speed 
shaft,  and  in  any  event  its  bearings  wear  pretty  fast.  If  in 
addition  you  add  the  strain  of  a  belt  the  wear  is  increased, 
and  wear  in  the  cam  shaft  bearings  has  an  immediate  and 
bad  effect  on  the  intermittent  movement,  and,  therefore,  on 
the  picture  on  the  screen.  My  advice  is  to  never  under  any 
circumstances  belt  your  motor  drive  to  the  fly  wheel  of  your 
projector.  I  would  also  advise  operators  and  managers  who 
build  a  home-made  motor  drive  to  limit  the  possible  crank 
shaft  speed  to  70.  Seventy  is  as  fast  as  any  projection  ma- 
chine ought  to  be  run  under  any  ordinary  conditions;  the 


Figure  118. 

limit  the  other  way  should  be  45;  below  that  the  fire  shutter 
is  apt  to  drop. 

Where  motor  driven  machines  are  in  use,  the  temptation  to 
the  operator  to  leave  his  machine,  at  least  for  short  intervals 
of  time,  is  strong.  The  manager  is  also  inclined  to  have  the 
operator  utilize  in  rewinding,  making  splices,  etc.,  what  ap- 


, FOR    MANAGERS    AND    OPERATORS 


279 


ToMOTOR  f- 


pears  to  him  to  be  wasted  time  while  the  picture  is  run- 
ning. Many  otherwise  good  operators  do  this,  too,  but  I 
cannot  condemn  the  practice  too  strongly.  I  have  said 
literally  hundreds  of  times,  and  I  say  again,  as  emphatically 
as  I  know  how,  that  WHILE  THE  PICTURE  is  ON  THE  SCREEN  THE 

OPERATOR  HAS  NO  BUSINESS  ANYWHERE  ELSE  UNDER  THE  SUN  EX- 
CEPT RIGHT  THERE  IN  FRONT  OF  THE  OBSERVATION  PORT  WATCHING 

THE  PROJECTION,  governing  the  speed,  and  regulating  his  light. 
The  temptation  to  leave  the  machine  is  still  greater  if  in  addi- 
tion to  a  motor  drive  an  arc  controller  is  used,  and,  in  some  high 
class  houses,  where  high  class  projection  is  -put  on,  I  have 
gone  into  the  operating  room  and  found  the  operator  away 
from  his  machine,  and  have  had  him  stand  and  talk  to  me 
for  as  long  as  two 
or  three  minutes 
while  the  motor  and 
the  arc  controller 
ran  the  show.  The 
fact  that  there  was 
no  fault  in  the 
screen  illumination 
during  that  time 
does  not  alter  the 
fact  that  there  might 
have  been,  and  if 
there  had  been  the 
operator  would  not 
have  known  it,  and 
certainly  he  was  in  no  position  to  properly  regulate  the  speed  of 
his  projector  under  the  varying  conditions  met  with  in  different 
scenes  of  the  film.  I  must  again  impress  upon  operators 
the  fact  that  if  they  themselves,  by  their  actions,  convey  the 
idea  to  the  manager  that  it  is  not  necessary  to  watch  the 
picture,  govern  the  machine  speed,  and  be  on  the  job  every 
minute  of  the  time  the  picture  is  running,  the  manager  is 
very  likely  to  become  imbued  with  the  idea  that,  equipped 
with  a  motor  drive  and  an  arc  controller,  there  is  no  large 
need  for  high  grade  skill  in  the  operator  himself.  This  view 
is  wrong,  from  any  and  every  point  of  view,  but  nevertheless 
if  managers  get  that  idea  operators  have  none  but  themselves 
to  blame.  I  would  also  like  to  impress  upon  the  minds  of 
operators  the  fact  that  when  the  manager  gets  the  aforesaid 
idea  fixed  in  his  mind  it  is  prettly  hard  to  convince  him  that 
there  is  any  need  of  paying  operators  good  salaries.  The 
moral  of  this  is:  stay  at  your  machine,  watch  the  picture, 


Figure  119. 


280  MOTION    PICTURE   HANDBOOK 

graduate  your  speed  to  fit  the  movement  in  the  film,  and 
let  tl*e  manager  understand  that,  while  automatic  arc  con- 
trollers and  motor  driven  machines  improve  conditions  and 
results,  still  by  no  manner  of  means  do  these  lessen  the 
necessity  for  knowledge  and  skill  on  the  part  of,  the  operator 
himself. 

WALSTAD  PROJECTION  STAND.— MODEL  D 

The  Walstad  Machine  Company,  Tacoma,  Washington, 
constructs  a  very  substantial,  rigid  stand,  designed  to  allow 
the  driving  of  two  or  more  projection  mechanisms  of  any 
standard  make  with  one  motor,  the  motor  driving  a  counter- 
shaft which  is  equipped  with  separate  clutches  for  each  of 
the  projection  mechanisms,  as  well  as  a  friction  for  driving 
the  rewind,  which  is  also  located  on  the  stand  between  the 
projection  machines.  There  is  also  a  large  substantial  fric- 
tion, by  means  of  which  the  speed  of  the  projection  mech- 
anisms may  be  varied  at  will.  One  advantage  of  this  ar- 
rangement is  that  the  speed  of  both  projection  mechanisms 
is  precisely  the  same  when  dissolving  from  one  picture  to 
the  next. 

All  machine  controls  are  located  in  such  manner  that  the 
operator  is  enabled  to  handle  the  equipment  with  ease, 
efficiency,  dependability  and  safety.  The  operator  handles 
both  machines  and  the  rewind  while  standing  or  seated  be- 
tween the  projectors — a  very  favorable  feature  where  one 
operator  is  compelled  to  do  the  rewinding  in  addition  to 
handling  both  projectors.  I  object  strenuously  to  the 
operator  doing  the  rewinding,  but  that  is  nevertheless  the 
practice  in  many  theatres. 

In  order  to  accomplish  this  the  magazines  of  the  right- 
hand  machine  are  reversed  (full  directions  for  accomplishing 
this  accompany  the  outfit),  so  that  the  operator  threads  the 
right-hand  machine  from  the  left-hand  side.  This  is  rather 
awkward  at  first,  but  he  soon  gets  the  knack  of  it,  and  he 
can  then  thread  just  as  readily  from  one  side  as  the  other. 

Another  feature  is  a  brake  on  the  unwinding  reel  of  the 
rewind.  This  brake  is  automatic  in  its  action,  and  by  its  use 
the  film  is  wound  tightly  upon  the  reel,  which  eliminates 
the  necessity  of  using  the  hand  as  a  brake  and  "pulling 
down,"  which  latter  operation  is  responsible  for  much  of  the 
damage  to  film. 

The  main  driving  shaft  is  mounted  upon  a  separate  frame, 
to  which  is  also  attached  the  motor,  thus  making  the  power 
section  a  complete  unit  within  itself.  This  unit  is  attached 


FOR   MANAGERS   AND    OPERATORS 


281 


to  the  main  stand  by  means  of  two  brackets,  as  can  be  seen 
in  figures  120  and  121. 

The  stand  is  substantially  constructed  of  iron  and  steel 
throughout.  It  is  rigid  and. so  braced  that  vibration  is  re- 
duced to  a  minimum.  There  is  also  provision  for  all  neces- 
sary adjustments,  so  that  the  operator  can  readily  set  the 
apparatus  to  give  any  desired  pitch  in  projection.  The  motor 
belt  is  very  heavy  and  substantial.  This  stand  has  been  in 


Figure  120. 

use  on  the  Pacific  Coast  for  some  years,  and  is  no  longer 
an  experiment.  Where  the  Walstad  stand  is  installed,  the 
theatre  will,  of  course,  only  purchase  the  projection  mech- 
anisms, lamphouses  and  magazines. 

Fig.    121   gives   a  very  good  idea   of  the     quipment  as   a 
whole.     The  bases  upon  which  are  mounted  the  projection 


282  MOTION    PICTURE    HANDBOOK 

mechanisms  are  shown  at  1-1.  They  are  made  to  fit  any 
standard  projection  machine.  Provision  has  been  made  to 
attach  the  lower  .magazine  to  the  underside  of  the  bases.  In 
the  case  of  the  right-hand  machine  the  upper  and  lower 
magazines  are  reversed,  so  that  the  doors  open  toward  the 
center  of  the  projection  stand,  as  has  already  been  noted; 
2-2  are  the  bases  upon  which  are  mounted  the  lamphouses. 
These  are  also  made  to  fit  the  various  standard  lamphouses; 
3  is  the  motor  which  drives  the  complete  equipment,  and  may 
be  had  for  either  A.  C.  or  D.  C.  The  base  to  which  the 
motor  is  attached  is  so  made  that  it  will  accommodate  any 
standard  motor  of  suitable  size;  4-4  are  the  clutches  by 
means  of  which  the  projection  mechanisms  are  driven;  5  is 
the  rewind  drive;  6  is  a  glass  inserted  in  the  steel  plate,  with 


Figure  121. 

a  low  C.  P.  incandescent  lamp  underneath  for  making  patches 
and  for  inspection;  7-7  are  the  handles  which  control  the 
clutches;  8-8  show  the  method  of  adjustment  for  pitch  by 
means  of  screws,  there  being  a  similar  arrangement  on  the 
rear  legs.  In  Fig.  120  they  are  shown  more  clearly;  9-9  are 
lamp  sockets,  designed  to  hold  incandescent  lamps  which 
swing  in  front  of  the  lens  during  threading,  for  the  purpose 
of  framing;  they  may  also  be  used  for  locating  proper  posi- 
tion of  carbons  after  trimming  the  lamp. 

To  Operate  Stand. — Place  framing  light  in  front  of  the 
objective  of  the  left-hand  mechanism.  Thread  film  in  usual 
way.  Remove  left-hand  framing  light.  The  motor  having 


FOR    MANAGERS    AND    OPERATORS 


283 


been  started,  all  that  is  necessary  to  start  the  left-hand 
machine  is  to  drop  the  opening  lever  into  operating  position. 
If  the  speed  of  the  machine  is  not  satisfactory,  move  the 
control  lever  toward  the  motor  to  decrease  speed,  or  away 
from  the  motor  to  increase  it.  Having  got  left-hand  head 
under  way  at  the  proper  speed,  proceed  to  thread  the  right- 
hand  head  the  same  as  you  did  the  other.  When  the  time 
comes  to  change  over,  all  that  is  necessary  is  to  drop  the 
operating  lever  of  the  right-hand  machine  into  operating 
position,  after  first  striking  your  arc,  of  course,  and  when 
the  dissolve  is  completed  pull  the  lever  of  the  left-hand 
machine  into  non-operating  position. 

In  changing  from  one  reel  to  the  other  no  attention  need 
be  paid  to  the  speed  of  the  machine,  unless  it  is  desirable 
because  of  the  action  in  the  picture,  since  both  machines 
will,  of  necessity,  be  running  at  precisely  the  same  rate  of 
speed.  If  it  is  desired  to  run  the  show  to  schedule  this  may 
be  done  by  observing  the  location  of  the  lever,  according  to 
the  marks  on  its  segment. 

The  author  has  personally  examined  this  equipment  a. id 
pronounces  it  first-class  in  every  respect. 


Opportunities  have  no 
schedule  time!  You 
must  be  at  the  station 
when  they  arrive. 


284  MOTION    PICTURE    HANDBOOK 


Carbons 


THE  very  foundation  of  the  projection  of  pictures,  either 
moving  or  otherwise,  is  light,  and  light  for  projection 
purposes  depends,  to  a  very  great  extent,  upon  the 
electrodes  (carbons)  with  which  it  is  produced. 

Each  form  of  arc  lighting  requires  the  use  of  carbons 
differing  in  material,  physical  characteristics  and  methods  of 
manufacture.  For  projection  work  it  would  be  utterly  im- 
practicable to-  use  either  very,  hard  carbons  or  the  com- 
paratively soft,  solid,  impregnated  flame  carbons.  If  one 
attempted  to  use  these  carbons  the  result  on  the  screen 
would  be  far  from  satisfactory. 

The  National  Carbon  Company  has  very  kindly  consented 
to  describe  for  us  in  detail  the  process  of  carbon  manufac- 
ture as  follows. 

Manufacture. — The  manufacture  of  projection  carbons  re- 
quires more  care  than  any  other  type  of  lighting  carbons, 
on  account  of  the  necessity  for  high  candle  power,  steadiness, 
reliability,  color  and  other  features.  The  basis  of  the  pro- 
jection carbons  is  lampblack,  the  purest  form  of  carbon 
known.  Even  the  ordinary  lampblack  used  in  the  manufac- 
ture of  other  types  of  lighting  carbons  contains  far  too 
much  ash  to  be  used.  Therefore  a  special,  selected  black  is 
employed.  Even  this  material  contains  considerable  volatile 
matter,  which  is  driven  off  by  calcination  at  a  high  tempera- 
ture. This  calcined  material  is  known  as  "carbon  flour," 
and  is  so  pure  that  it  is  less  than  one-twentieth  of  1  per 
cent,  ash,  and  contains  little  or  no  volatile  matter.  To  this 
flour  is  then  added  a  high  grade  binder  and  it  is  machine- 
mixed  into  a  stiff  mass,  in  a  fashion  very  similar;  to  that 
employed  in  kneading  bread  dough,  after  which  it  is  made 
up  into  plugs  and  fed  into  the  cylinders  of  hydraulic  presses, 
which  force  it  through  suitable  dies.  As  it  comes  from  the 
presses  the  carbon  is  allowed  to  run  on  grooved  boards, 
made  for  the  purpose.  It  is  now  in  the  form  of  rods,  approx- 
imately four  feet  long.  Carbons  which  are  to  be  cored  are 
forced  with  a  central  hole  throughout  their  length,  made  by 
having-  a  steel  pin  fixed  in  the  center  of  the  hole  in  the  die. 
The  carbons  are  now  ready  for  baking. 


FOR    MANAGERS   AND    OPERATORS  285 

The  form  of  the  binder  contained  in  the  green  carbon  must  be 
changed  by  driving  off  the  volatile  matter  therein  and  depositing 
the  rest  throughout  the  electrode  in  the  form  of  pure  carbon. 
Inasmuch  as  the  quality  of  the  finished  carbon  depends  on 
the  method  and  temperature  of  the  baking,  this  is  one  of 
the  most  important  operations  in  its  manufacture.  The  green 
carbons  are  first  packed  in  special  cylinders,  to  keep  them 
from  becoming  crooked,  and  to  protect  them  from  injury, 
and  are  then  placed  in  ga&fired  furnaces  specially  designed 
to  secure  uniform  heating',  from  which,  during  the  process 
of  baking,  air  is  excluded.  The  total  operation  of  packing, 
baking,  cooling  and  unpacking  takes  from  three  weeks  to  a 
month. 

After  removal  from  the  furnace  the  carbons  are  cut  to 
proper  length  and  sorted  for  straightness.  Owing  to  varia- 
tion in  shrinkage  during  the  baking  process,  some  deviation 
from  perfect  straightness  must  be  expected.  The  solid  and 
hollow  carbons  are  now  separated.  The  former  are  taken 
directly  to  the  pointing  machine,  after  which  they  are  ready 
for  shipment;  the  latter  go  to  the  coring  department.  Here 
the  central  hole  through  the  carbon  is  filled  with  the  core 
material,  which  is  a  non-flaming  but  arc-supporting  sub- 
stance. It  is  mixed  into  a  thin  paste  with  water  glass,  a 
soluble  alkaline  silicate,  which  becomes  solid  when  dried. 
This  core  material  is  forced  into  the  hole,  and  the  carbons 
are  then  rebaked  for  a  short  time  at  a  comparatively  low 
temperature,  in  order  to  solidify  the  cores,  and  this  opera- 
tion completes  the  process  of  manufacture. 

The  purpose  of  the  core  is  as  follows:  At  its  incandescent 
tip  it  supplies  a  far  greater  amount  of  arc-supporting  gas 
than  does  the  carbon  composing  the  shell,  and,  therefore 
a  path  of  lower  resistance  is  offered  between  core  and  core, 
as  in  the  A.  C.  arc,  or  between  core  and  solid  carbon  tip  as 
in  the  D.  C.  arc,  than  between  two  solid  carbons.  Hence 
the  arc  tends  to  emanate  from  the  core,  instead  of  wander- 
ing all  over  the  face  of  the  carbon.  The  practical  effect  of 
the  core  is  to  hold  the  light  steady.  If  a  solid  upper  carbon 
were  used  the  light  would  jump  from  side  to  side  and  up 
and  down,  causing  constantly  recurring  shadows  upon  the 
screen.  It  would  be  utterly  impossible  to  secure  a  good, 
steady  light  with  two  solid  carbons  or  with  a  solid  tipper 
carbon. 

Size  of  Carbons. — The  size  of  carbons  is  a  subject  ap- 
proached with  considerable  hesitation.  There  is  a  growing 
tendency  among  operators  to  use  three-quarter  inch  cored 


286  MOTION    PICTURE    HANDBOOK 

above  and  five-eighth  inch  cored  or  solid  below,  or  anything 
between  40  and  50  amperes  D.  C.  This  practice  is  approved 
by  some  of  the  best  operators  in  the  country — men  in  whose 
judgment  I  have  confidence.  They  have  tried  five-eighth 
inch  above  and  below,  five-eighth  inch  above  and  one-half 
inch  below,  three-quarter  inch  cored  above  and  below,  three- 
quarter  inch  cored  above  and  three-quarter  inch  solid  below, 
and  have  finally  decided  that  the  three-quarter  inch  cored 
above  and  five-eighth  inch  cored  or  solid  below  is  best. 
Therefore,  I  recommend  those  sizes  to  operators  using  be- 
tween 40  and  50  amperes  D.  C.  There  is  considerable  difference 
of  opinion  as  to  whether  the  lower  carbon  be  solid  or  cored; 
therefore  I  would  advise  each  operator  to  try  both  and  decide 
for  himself  which  gives  best  results  in  his  case.  Between  20 
and  40  amperes  I  would  advise  five-eighth  inch  cored  above 
and  one-half  inch  cored  or  solid  below  for  D.  C.  Below  20 
amperes  D.  C.  I  think  one-half  inch  cored  above  and  three- 
eighth  inch  solid  or  cored  below  will  serve  the  purpose 
very  well.  For  A.  C.  on  anything  below  60  amperes  I  would 
recommend  two  five-eighth  inch  cored  carbons  above  and 
below,  and  above  60  amperes,  say  up  to  80,  two  three-quarter 
inch  cored.  Some  operators  using  A.  C.  prefer  a  lower  carbon 
of  smaller  diameter,  so  that  it  will  needle  considerably.  This  is 
a  matter  upon  which  I  cannot  pass,  each  one  must  experiment 
and  decide  for  himself. 

Solid  vs.  Cored  Lower. — The  objection  to  a  solid  lower 
carbon  for  D.  C.  is  that  it  does  not  maintain  as  steady  an  arc 
as  with  two  cored  carbons.  The  objection  to  a  cored  lower  car- 
bon is  that,  while  it  helps  maintain  a  steady  arc,  this  is  only 
true  by  reason  of  the  increased  volume  of  gas  emanating  from 
the  lower  core,  and  this  forms  a  curtain  in  front  of  the  crater, 
and  materially  diminishes  the  illumination. 

I  would  not,  under  any  circumstances,  advise  the  use  of 
less  than  40  amperes  A.  C.  for  the  projection  of  moving 
pictures.  For  stereopticon,  however,  the  amperage  may  run 
as  low  as  25,  or  possibly  even  20  if  the  picture  be  a  small  one 
and  the  screen  of  a  semi-reflective  type. 

As  against  the  above  the  National  Carbon  Company  pro- 
poses the  following,  with  reference  to  carbon  sizes  and  com- 
binations, and,  inasmuch  as  it  comes  from  a  large  carbon 
manufacturing  company,  it  is  certainly  entitled  to  very  seri- 
ous consideration  on  the  part  of  operators.  It  will  be 
observed  that  the  recommendations  made  by  the  National 
are  pretty  closely  in  accord  with  those  made  by  the  author, 


FOR    MANAGERS    AND    OPERATORS 


287 


and,  inasmuch  as  each  arrived  at  his  conclusion  entirely  in- 
dependent of  the  other,  I  feel  rather  flattered  to  know  that 
my  recommendation  coincides  so  nearly  with  vhat  of  the 
manufacturer. 


ALTERNATING    CURRENT 
Amperage     Upper 
70-80         %"    cored 
60-70         %"    cored 
50-60         %"    cored 
45-50    9/16"    cored 


CURRENT 
Lower 

DIRECT    GUI 
Amperage      Upper 

IRENT 
Lower 

%"   cored 

55 

%"   cored 

%"   cored 

%"    cored 

50 

%"   cored 

%"   solid 

%"   cored 

45 

%"   cored 

%"  solid 

9/16"    cored 

or  cored 

%"   cored 

9/16"   solid 

40 

%"   cored 

%"   solid 

25 

9/16"    cored 

7/16"    solid 

20 

%"   cored 

r</16"    solid 

Inspection. — When  purchasing  carbons  the  operator  or 
manager  should  inspect  them  for  faults.  Cracks  running 
lengthwise  of  the  carbons  do  no  harm.  They  are  in  ,a  way 
characteristic  of  the  product,  and  are  caused  by  the  stiffness 
of  the  paste  from  which  they  are  formed.  Deep  cracks 
running  around  the  circumference,  however,  condemn  the 
carbons,  since  there  would  be  a  tendency  to  break  off  at 
these  points.  Hair  cracks  running  around  the  circumference, 
however,  are  often  found  in  good  carbons;  they  are  due  to 
the  same  cause  as  the  longitudinal  cracks  and  are  of  no  con- 
sequence. 

Hard  Spots. — There  is  possibly  no  other  one  thing  so 
trying  to  the  operator  as  carbons  containing  hard  spots.  When 
the  arc  strikes  a  hard  spot  in  the  carbon  the  light  will  jump 
and  sputter,  in  spite  of  everything  that  can  be  done,  until  the 
spot  has  burned  away.  These  spots  are  belived  to  be  caused 
by  a  lack  of  thorough  mixing  in  the  early  stages  of  manu- 
facture. The  manufacturers  of  the  best  carbons  have  prac- 
tically eliminated  this  most  serious  fault. 

Hard  and  Soft. — Carbons  that  are  too  hard  have  a  tendency 
to  produce  a  yellow  light  through  faulty  cratering  and  slow 
burning,  with  resultant  short  arc.  These  things  naturally 
result  in  an  unsteady  light  of  low  intensity.  On  the  other 
hand  carbons  that  are  too  soft  burn  away  quite  rapidly,  but 
usually  give  a  good  light  while  they  last. 

Stubs. — Modern  projection  lamps  accommodate  6  inch 
lower  and  10  or  12  inch  upper  carbons.  This  eliminates  much 
waste,  as  against  two  6  inch  carbons,  since  there  is  just  so 
much  "stub  end"  to  each  carbon,  whether  the  carbon  be  6 


288  MOTION    PICTURE   HANDBOOK 

inches  or  10  inches  long.  In  other  words,  if  you  are  using 
6  inch  carbons  and  are  able  to  burn  them  down  until  there 
is  an  average  of  2  inch  of  stub  left,  you  will  be  wasting  one- 
third  of  each  carbon;  on  the  other  hand,  if  it  be  a  12  inch 
carbon  the  two  inches  of  necessary  waste  would  only  be  one- 
sixth  of  the  carbon;  therefore,  the  doubling  of  the  length 
of  the  carbon  cuts  the  waste  in  half. 

There  are,  however,  those  who  claim  that  the  additional 
resistance  of  the  long  carbon  is  objectionable.  The  fact  of 
the  matter  is,  however,  that  the  difference  as  between  a 
6  inch  and  a  12  inch  carbon  is  too  small  a  matter  to  be 
seriously  considered,  particularly  in  view  of  the  fact  that  the 
resistance  of  a  carbon  decreases  as  its  temperature  increases.  At 
any  rate  the  constant  annoyance  of  being  obliged  to  reset 
the  carbon  every  reel,  together  with  the  relatively  large 
waste  in  carbon  stubs  where  short  carbons  are  used,  more 
than  balances  the  extra  resistance  loss  of  the  long  carbon. 
Actual  experiments  made  by  the  writer  show  that  with  50 
amperes  flowing  through  a  closed  circuit  the  insertion  of 
10  inches  of  a  five-eighth  inch  cored  carbon  only  reduced 
the  current  flow  one  ampere. 

Chemicalizing  the  Carbon. — Many  operators  have  experi- 
mented on  a  small  scale  in  "chemicalizing"  carbons,  and  in 
the  opinion  of  the  author,  when  it  is  rightly  done,  salt  soaking 
has  beneficial  effect.  Concerning  this,  however,  the  National 
Carbon  Company  has  the  following  to  say:  "There  is  an 
impression  current  in  some  quarters  that  if  the  carbons  are 
soaked  in  common  salt  brine,  the  harshness  so  frequently 
found  in  the  light  emanating  from  the  A.  C.  arc  can  be  soft- 
ened and  improved.  This  is  a  fallacy,!  inasmuch  as  the 
salt  will  almost  immediately  volatize  out  as  soon  as  the 
electrodes  become  heated  by  the  high  current  passed  through 
them,  and  none  of  this  material  ever  actually  gets  into  the 
arc." 

Now,  with  all  due  respect  to  the  manufacturer  in  question, 
I  am  unable  to  agree  with  this,  because  what  I  have  seen  I 
have  seen,  and  I  certainly  have  witnessed  an  improvement 
in  the  light  for  which  I  could  find  no  other  explanation  ex- 
cept salt  soaked  carbons.  Untreated  carbons  placed  in  the 
same  lamp  did  not  produce  the  same  effect.  It  is,  however, 
only  fair  to  manufacturers  of  carbons  to  say  they  spend 
much  time  and  money,  or  at  least  the  American  manufac- 
turers do,  and  I  presume  the  foreign  also,  in  experiment- 
ing with  chemicals,  in  an  effort  to  procure  a  product  equal 


FOR    MANAGERS   AND    OPERATORS  289 

if  not  superior  to  their  competitors'  brands  at  the  same  or 
lower  cost.  They  have  carried  on  exhaustive  experiments 
on  every  point  which  in  their  estimation  can  have  any  pos- 
sible influence  on  the  operation  of  the  arc.  With  their  ex- 
tensive laboratories  and  research  department  they  have  vastly 
better  facilities  for  carrying  on  these  experiments  than  the 
operator  could  possibly  have.  Therefore  I  would  suggest 
that  when  an  operator  discovers  something  he  believes  will 
be  beneficial  let  him  communicate  with  the  Projection  De- 
partment of  the  Moving  Picture  World,  which  will  lay  the 
matter  before  the  manufacturers. 

Care  of  Carbons. — Carbons  should  invariably  be  kept  in  a 
dry  place  where  they  will  not  absorb  moisture,  since  mois- 
ture in  the  carbons  will  be  detrimental  to  projection  light. 


EQUIVALENTS 

Since  both  lens  and  carbon  diameter  measurements  are 
often  quoted  in  millimeters  it  is  advisable  that  the  operator 
know  what  a  millemeter  means  in  fractions  of  an  inch. 

One  millimeter  equals  .03937  of  an  inch,  or  roughly  one- 
twenty-sixth  of  an  inch.  The  equivalents  from  10  to  26  are 
as  follows: 

TABLE  5. 

Fractions  of  an  Inch 
Millemeters  in  Decimals  Roughly 

10  .3937  or    4/10  inch 

15  .59055  or    6/10  inch 

16  .62992 

17  .66929 

18  .70866      or  7/10  inch 

19  .74803      or  3/4  inch 

20  .78740 

21  .82677      or  8/10  inch 

22  .86614 

23  .90551  or    9/10  inch 

24  .94488 

25  .98425 

26  1.02362  or    1        inch 

Any  millimeter  measurement  may  be  reduced  to  inches  by 
multiplying  by  .03937.  One  centimeter  equals  .3937,  or  prac- 
tically four-tenths  of  an  inch.  One  meter  equals  39.37  inches, 
or  3.28  feet,  or  1.094  yards. 


290  MOTION    PICTURE    HANDBOOK 

SETTING  THE  CARBONS 

This  is  a  subject  second  to  none  in  importance.  A  very 
slight  difference  in  the  set  of  the  carbons  may  make  a  very 
large  difference  in  screen  illumination,  particularly  when 
using  A.  C. 

Practically  all  illumination  available  for  use  comes  from 
what  is  known  as  the  "crater."  With  D.  C.  there  is  only 
one  crater,  but  with  A.  C.  there  are  two.  The  crater  always 
forms  on  the  positive  carbon.  With  D.  C.  one  carbon  is 
always  positive  and  the  other  always  negative,  therefore  the 
entire  force  of  the  current  is  expended  toward  the  forming 
of  a  crater  of  ample  dimension  on  one  carbon,  the  positive; 
hence  it  is  imperative  that  the  positive  wire  be  connected 
to  the  upper  carbon.  As  has  been  said,  the  crater  always 
forms  on  the  positive  carbon,  but,  remembering  that  with  A. 
C.  each  carbon  is  alternately  positive  and  negative  many 
times  each  second,  we  readily  see  that  a  crater  will  be 
formed  on  both  carbons,  since  both  are  positive  half  the 
time.  It  therefore  follows  that  if  the  crater-forming  force  of 
the  current  is  divided  between  two  carbons,  the  craters  will 
be  much  smaller  than  if  an  equal  amperage  of  D.  C.  were 
used,  the  entire  energy  of  which  would  be  directed  toward 
forming  one  crater. 

The  light  giving  power  depends  upon  (a)  the  temperature 
of  the  crater;  (b)  its  area;  (c)  the  character  of  the  carbon. 
The  temperature  of  the  electric  arc  has,  so  far  as  I  know, 
never  been  actually  measured.  It  has,  however,  been  esti- 
mated as  high  as  8000  degress  C.  I  do  not  know,  but  it  is  the 
natural  inference  that,  since  the  force  of  A.  C.  is  divided 
between  two  craters,  and  the  full  force  directed  to  one  crater 
with  D.  C.,  the  temperature  of  the  D.  C.  crater  would  be 
higher,  assuming  the  amperage  in  each  to  be  equal.  Be  this 
as  it  may,  however,  with  equal  amperage  the  A.  C.  crater 
is  very  much  smaller  than  the  D.  C.  crater,  nor  is  the  com- 
bined area  of  the  crater  on  both  upper  and  lower  A.  C. 
carbons  equal  to  the  area  of  the  single  D.  C.  crater,  where 
equal  amperage  is  used.  See  Limit  of  Amperage,  Page  292. 

Taking  all  these  facts  into  consideration,  it  will  be  seen 
that  it  is  very  doubtful  whether  40  amperes  A.  C.  would 
produce  a  total  candle  power  equal  to  that  produced  by  40 
amperes  D.  C.,  but,  laying  that  question  aside,  and  even  al- 
lowing the  candle  power  would  be  equal,  the  fact  still  remains 
that  it  is  utterly  impossible  to  utilize  nearly  so  great  a  por- 
tion of  the  alternating  current  illumination  for  projection 
purposes  as  can  be  utilized  when  using  D.  C.  Referring  to 


FOR    MANAGERS   AND    OPERATORS  291 

Fig.  123,  Page  295,  and  Fig.  124,  Page  297,  this  is  made  clear 
by  the  examination  of  sketch  C  in  both  figures,  which  in 
both  instances  illustrates  an  ideal  crater  condition,  one  D.  C. 
and  one  A.  C.  It  will  be  observed  that  at  B,  Fig.  123,  the 
crater  is  of  ample  dimensions,  facing  the  lens  in  such  manner 
that  the  strongest  light  hits  pretty  nearly  the  center  of  the 
condensing  lens.  In  sketch  C,  Fig.  124,  the  crater  sets  at 
more  of  an  angle  to  the  lens;  also  it  is  very  much  smaller. 
The  result  of  all  this  is  that 

While  it  is  possible  to  secure  just  as  brilliant  an  illumina- 
tion with  A.  C.  as  with  D.  C.  it  will  require  practically  double 
the  amperage  to  do  so.  In  other  words,  it  will  take  close  to  80 
ampere  A.  C.  to  produce  a  screen  illumination  equal  to  that 
produced  by  40  amperes  D.  C. 

Operators  will  note  that  when  the  carbon  tips  are  cold 
they  may  be  brought  very  close  together  without  any  effect. 
They  must,  in  fact,  be  brought  into  actual  contact  before 
there  is  any  result.  It  will  also  be  noted  that  although  the 
carbon  tips  may  be  separated  from  one-quarter  inch  to  three- 
eighths  inch  when  the  arc  is  burning  normally,  if  the  switch 
be  opened,  thus  breaking  the  arc,  and  be  immediately  closed 
again,  the  current  will  leap  the  gap  and  the  arc  will  reset 
itself  between  the  still  incandescent  carbon  points.  This 
phenomenon  is  due  to  the  fact  that  the  carbon  is  volatized 
(transformed  into  a  gaseous  vapor)  by  the  tremendous  heat 
of  the  arc,  and  this  vapor  in  itself  forms  an  electrial  con- 
ductor, though  one  of  tolerably  high  resistance,  while  the 
air  itself  is  a  very  poor  conductor  of  electricity — in  fact  an 
insulator.  When  the  carbons  are  cold,  or  only  red,  they  are 
not  being  volatized;  therefore  the  vapor  (often  referred  to 
as  the  "arc  stream")  is  not  present;  there  is  only  air  between 
the  carbon  tips,  and  air  presents  too  great  a  resistance  to 
allow  the  current  to  leap  from  one  carbon  point  to  the  other, 
even  when  the  tips  are  very  close  together.  For  one,  two 
or  maybe  three  seconds  after  the  arc  is  shut  off,  however, 
the  carbon  still  continues  to  be  volatized,  and,  therefore,  the 
vapor  is  present,  and  the  space  between  the  carbon  tips  still 
bridged  by  the  gaseous  conducting  medium. 

The  commonly  accepted  explanation  of  the  formation  of 
the  crater  on  the  carbon  tip  is  that  minute  particles  are  torn 
away  from  the  positive  carbon  by  the  current.  These  par- 
ticles are  mostly  volatized  as  soon  as  they  are  torn  off, 
though  some  of  them-  reach  and  are  deposited  on  the  nega- 
tive carbon  tip,  only  to  be  volatized  there  later.  The  writer 


292  MOTION    PICTURE    HANDBOOK 

does  not  pretend  to  vouch  for  the  correctness  of  this  theory. 
It  is  given  for  what  it  is  worth. 

Limit  of  Amperage. — As  previously  stated,  the  larger  a 
crater  of  given  temperature  the  more  light  will  emanate  there- 
from. See  computing  C.  P.  of  arc,  Page  293.  There  is,  how- 
ever, an  economic  limit  to  possible  light  gain  through  increased 
size  of  crater,  if  the  light  must  be  passed  through  a  4^  inch 
diameter  projection  machine  condensing  lens  system.  The 
theoretical  light  source  to  work  in  perfect  accord  with  the 
optical  principle  involved  in  a  lens  system  is  a  pinpoint, 
meaning  a  light  the  size  of  the  point  of  a  pin.  As  the  area  of 
the  light  source  increases,  the  ability  of  the  lens  system  to 
utilize  the  light  is  rapidly  decreased,  until  a  point  is  reached 
where  any  further  gain  of  light  through  increase  of  area  of 
the  light  source  is  only  made  at  heavy  expense.  More  than 
three  years  ago  I  said  that  this  point  was  reached  when  the 
crater  becomes  one-half  inch  in  diameter.  I  am  still  con- 
vinced that  that  statement  is  approximately  correct.  See 
"Matching  the  Lens  System,"  Page  113;  for  further  explana- 
tion and. data,  also  see  Amperage,  Page  157. 

This  means  that  the  economic  limit  of  light  for  projection 
purposes  lies  between  50  and  60  amperes  D.  C.,  and  between 
80  and  100  A.  C.,  because  the  60  ampere  D.  C.  crater  will 
be  fully  one-half  inch  in  length  by  almost  that  in  width; 
therefore  any  further  increase  in  amperage  will,  if  my  theory 
is  correct,  be  of  comparatively  slight  value. 

I  believe  it  is  safe  to  say  that  beyond  60  amperes  D.  C.,  and 
perhaps  90  A.  C.,  not  more  than  25  per  cent,  of  the  energy  ex- 
pended will  appear  on  the  screen  in  the  shape  of  illumination. 

A  projection  arc  must  be  operated  with  the  carbon  tips  a 
certain  given  distance  apart,  in  order  to  obtain  the  best 
results,  and  this  distance  will  vary  according  to  the  number 
of  amperes  used,  the  size  of  the  carbons,  etc.  It  follows, 
therefore,  that,  inasmuch  as  the  carbon  tips  of  a  hand-fed 
projection  lamp  cannot  be  kept  precisely  the  same  distance 
apart  constantly  and  under  all  conditions,  the  arc  voltage 
will  vary.  Arc  voltage  is  the  pressure  necessary  to  force 
the  current  across  the  space  between  the  carbon  tips. 

This  equals  the  reading  of  the  voltmeter  when  it  is  attached 
to  the  upper  and  lower  carbon  arms  when  the  arc  is  adjusted 
.for  perfect  screen  illumination.  It  is,  however,  the  number 
of  amperes  flowing,  not  the  voltage,  which  determines  the 
size  of  the  crater,  hence  the  amount  of  light  it  will  produce 


FOR   MANAGERS   AND    OPERATORS  293 

In  this  connection  let  us  pause  and  consider  the  C.  P.  of 
the  crater.  It  has  been  discovered  by  experiment  that  the 
brilliancy  of  the  positive  carbon  crater  is  practically  con- 
stant, regardless  of  amperage  consumed,  at  approximately 
158  C.  P.  per  square  millimeter  where  solid  carbons  are 
used,  and  130  C.  P.  where  cored  carbons  are  used.  We  are 
not  interested  in  solid  carbons,  but  for  cored  carbons  this 
would  mean  a  total  crater  brilliancy  of  130  muliplied  by  the 
square  millimeter  area  of  the  crater.  This  figures  out  at 
41,860  C.  P.  for  a  crater  having  an  area  of  V-2.  square  mch.^ 

From  this  it  will  be  seen  that  increased  amperage  gives  in- 
creased illumination  at  the  rate  of  130  C.  P.  for  each  square 
millimeter  of  additional  area  of  crater. 

It  will  also  be  seen  that,  the  spot  being  a  magnified  image  of 
the  crater,  it  is  highly  important^that  our  condenser  arrangement 
be  such  that  the  spot  be  given  its  normal  diameter  without 
withdrawing  the  arc  from  the  lens  beyond  the  distance  absolutely 
necessary  to  prevent  breakage. 

By  the  use  of  the  foregoing  the  operator  will  be  able  by 
estimating  the  area  of  his  crater  in  fractions  of  a  square 
inch,  or  in  millimeters,  to  compute  the  C.  P.  of  his  projec- 
tion arc  with  a  considerable  degree  of  accuracy. 

Simon  Henry  Gage  and  Henry  Phelps  Gage,  Cornell  Uni- 
versity, have  conducted  experiments  with  D.  C.  regular  carbon 
sets  which  resulted  as  follows  (See  their  "Optical  Projec- 
tion") :  Using  direct  current  and  regular  carbon  set,  as  per 
Fig.  123,  a  15  ampere,  50  volt  arc,  taking  current  through  a 
rheostat,  consuming  750  watts  in  the  lamp  and  1650  watts  in 
total  gives  a  total  C.  P.  of  3490,  or  4.65  C.  P.  per  watt  consumed 
in  the  arc,  or  2.12  C.  P.  per  total  watt  consumed  in  the  arc 
and  rheostat.  A  40  ampere,  51  volt  arc,  taking  current 
through  a  rheostat  consumes  2040  watts  in  an  arc  or  4400 
watts  in  total,  and  gives  12350  C.  P.,  which  is  6.05  C.  P.  per 
watt  consumed  in  the  arc,  or  2.8  C.  P.  per  watt  consumed  in 
both  the  arc  and  resistance. 

It  will  be  observed  from  this  that  as  the  amperage  in- 
creases, voltage  remaining  essentially  the  same,  the  light 
giving  power  per  watt  becomes  considerably  greater.  At 
40  amperes  there  is  a  gain  of  1.4  C.  P.  per  watt  of  energy 
expended  in  the  arc,  and  .68  of  a  C.  P.  per  watt  expended 
in  the  combined  arc  and  rheostat,  as  against. the  15  ampere 
arc. 

In  these  experiments  it  was  shown  that  a  mercury  arc  recti- 
fier, using  40  amperes  at  52  volts,  same  carbon  set,  gave 
12150  C.  P.,  a  decrease  of  200  C.  P.  as  against  direct  current 


294 


MOTION    PICTURE    HANDBOOK 


from  a  generator  taken  through  a  rheostat,  which  seems  to 
indicate  that  the  loss  by  reason  of  pulsations  of  the  rectifier 
is  almost  negligible.  With  A.  C.,  same  carbon  set,  40  am- 
peres with  27  volts  at  the  arc  gave  1830  C.  P.,  or  2.42  C.  P. 
per  watt  expended  in  the  arc,  or  .70  of  a  C.  P.  per  watt  of 
total  energy  expended  in  the  arc  and  rheostat,  or  2.32  C.  P. 
per  watt  of  total  energy  expended  in  the  arc  and  transformer 
(economizer). 

Experiments  have  proved  that  there  is  but  little  difference 
in  actual  cost  per  C.  P.  in  light  from  an  alternating  current 
arc  taking  current  through  a  well  designed  transformer  (econ- 
omizer)     and      D.      C. 
through      a      rheostat, 
though    the    A.     C.    is 
much    less    satisfactory 
to    use    from    any    and 
every   point   of  view. 

"Optical  Projection," 
by  Simon  Henry  and 
Henry  Phelps  Gage, 
gives  the  following  ex- 
cellent chart  of  rela- 
tion between  power 
consumption  and  candle 
power.  By  this  chart  it 
will  be  seen  that  for  the 
power  consumed,  A.  C. 
through  a  rheostat  gives 
the  least  per  watt;  D.  C. 
through  a  rheostat  next; 
A.  C.  through  an  econ- 
omizer next,  and  A.  C. 
through  a  rectifier  best 
of  all,  but  the  chart  is 
presumably  plotted  for 

a  110  volt  supply,  taking  no  account  of  a  lower  voltage  supply. 
The  upper  left  hand  line  shows  that  if  only  the  actual  power 
consumed  in  the  arc  itself  be  considered,  then  D.  C.  has 
much  the  greater  efficiency.  Well,  I  am  not  good  at  plotting 
curves,  but  if  .we  consider  a  60  or  70  volt  D.  C.  supply,  such 
as  most  isolated  light  plants  used  by  theatres  deliver,  then 
D.  C.  through  a  rheostat  ought  to  have  an  efficiency  fully 
equal  to  the  rectifier  current,  or  possibly  even  of  considerable 
greater  efficiency. 


C 

| 

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1 

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1 

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y- 

L  x 

,' 

o 

> 

/ 

9 

«'. 

rt 

'•;, 

iV 

, 

Q 

(,£ 

,+ 

c<- 

; 

^i 

-0 

Power  Consumed 

/ 

,< 

Incli-r 

V 

bens 

4»L 

/ 

; 

<1 

v'>*'' 

/V 

Zoo* 

* 

,-H, 

- 

-" 

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-H 

lolDt] 

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j 

Figure  122. 


FOR    MANAGERS    AND    OPERATORS 


295 


This  is  a  little  digression  from  the  main  subject,  which  we 
will  now  resume. 

Position  of  the  Crater. — In  considering  light  for  projec- 
tion, however,  the  foregoing  must  be  coupled  with  another 
item  of  prime  importance,  viz.,  the  position  of  the  crater. 

This  latter  is  the  most  important  point  of  all,  since  no 
matter  what  amount  of  light  the  arc  may  be  producing,  if 
that  light  be  not  directed  toward  the  lens,  then  a  large  pro- 
portion of  it  or  even  perhaps  practically  all  of  of  it  will  be 


Figure  123. 

wasted.  If  the  crater  points  downward,  the  greater  per- 
centage of  light  will  be  thrown  in  that  direction,  as  is 
illustrated  at  A,  Fig.  123,  in  which  the  strongest  light  would 
follow  line  X,  and  only  a  very  slight  percentage  reach  the 
lens,  as  indicated  by  the  lines.  Such  a  setting  would  be 
enormously  inefficient. 

For  best  results  the  crater  must  be  exactly  in  line  with 
the  optical  axis  (center)  of  the  condensing  lens.  Inasmuch 
as  all  the  light  comes  from  the  crater,  it  therefore  follows 
that  the  more  squarely  the  crater  can  be  made  to  face 
the  condensing  lens,  without  causing  the  lower  carbon  tip 
to  interfere  too  much  in  the  light  ray,  the  greater  percentage 
of  light  will  reach  the  lens,  and  be  made  available  for  pro- 
jection. This  is  illustrated  in  Fig.  123,  in  which  A  shows 


296  MOTION    PICTURE    HANDBOOK 

a  highly  inefficient  D.  C.  setting;  B  a  setting  somewhat  more 
efficient,  but  still  not  a  good  one  because  the  crater  points 
too  much  downward,  and  the  strongest  light  would  follow 
line,  X,  thus  missing  the  lens  entirely.  C,  however,  is  an 
ideal  condition — that  is  to  say,  the  ideal  practical  condition, 
since,  for  certain  reasons  well  understood  by  operators,  it  is 
impossible  to  get  a  good  crater  and  have  it  squarely  face 
the  lens,  so  as  to  cause  the  strongest  light  to  pass  exactly 
through  the  center  of  the  lens.  Assuming  the  amperage  of 
arcs  A,  B,  C,  Fig.  123,  to  be  equal,  each  arc  would  give  off 
practically  the  same  amount  of  light,  but  that  of  A  and  B, 
being  misdirected,  would  not  illuminate  the  screen  nearly  so 
brilliantly  as  would  the  light  from  C. 

The  position  of  the  crater  is  controlled  by  (a)  the  angle  of 
the  lamp  and  (b)  the  relation  of  the  carbons  to  each  other. 
The  condition  at  A  is  the  result  of  setting  the  carbon  tips 
central  with  each  other,  as  per  1,  Fig.  123;  B  is  the  result 
of  advancing  the  lower  carbon  tip  slightly  ahead  (toward  the 
lens)  of  the  upper  carbon  tip,  as  per  2,  Fig.  123;  C  is  the 
result  of  advancing  the  lower  carbon  slightly  more  than  at 
3,  as  per  Fig.  123.  This,  however,  can  be  overdone,  as  is 
shown  at  D,  Fig.  123.  At  D  both  the  angle  of  the  lamp  and  the 
advancement  of  the  lower  carbon  is  too  great,  the  result  being 
that,  while  we  have  a  crater  facing  the  lens  squarely,  still  the 
advantage  thus  gained  is  neutralized  by  the  fact  that  the 
lower  carbon  tip  comes  between  the  crater  and  the  lens; 
also  at  Z  a  long  skirt  has  formed,  due  to  the  fact  that  the 
lower  carbon  has  been  advanced  too  far.  This  form  of 
crater  is  in  itself  inefficient,  and,  moreover,  when  the  arc  is 
shut  off  and  the  carbon  is  allowed  to  cool  the  skirt  is  apt 
to  break  off  about  midway  of  the  crater,  thus  utterly  ruining 
the  crater  and  very  seriously  injuring  the  illumination  until 
a  new  one  is  formed. 

Re-examining  C,  Fig.  123,  we  observe  that  the  lower  car- 
bon tip  begins  to  interfere  in  the  light  at  the  fourth  line 
down,  but  that  the  lower  line  from  the  lens  to  the  crater 
misses  the  carbon  tips  and  strikes  the  crater  above  its  center. 
This  is  about  as  good  a  condition  as  you  can  hope  to  obtain. 
These  sketches  are  not  designed  to  accurately  portray  actual 
arc  conditions  exactly  as  they  are,  but  merely  to  set  forth, 
in  understandable  form,  the  various  equations  which  enter 
into  the  matter  of  carbon  setting,  the  faults  which  must  be 
studied  and  guarded  against,  and  to  illustrate  the  best  obtain- 
able condition,  which  the  operator  should  strive  to  attain. 


FOR    MANAGERS   AND    OPERATORS 


297 


When  we  consider  the  alternating  current  arc,  however, 
we  encounter  an  entirely  and  a  radically  different  propo- 
sition; also  one  which  is  more  difficult  to  handle  where 
less  than  70  amperes  are  used.  As  already  explained,  the 
crater  will  form  on  both  carbon  tips  when  A.  C.  is  used,  since 
each  carbon  is  alternately  positive  and  negative  many  times 
each  second.  As  has  already  been  set  forth,  the  amount  of 
available  projection  light  will,  within  certain  limits,  be  in 
direct  proportion  to  the  area  of  the  crater,  how  squarely  it 
can  be  made  to  face  the  condenser,  and  kind  of  current. 
With  the  crater-producing  force  divided  between  two  car- 
bons, as  is  the  case  with  A.  C.,  it  follows  that  neither  crater 
will  be  as  large,  for  a  given  number  of  amperes,  as  would  be 


Figure  124. 

the  case  with  D.  C.,  with  which  the  whole  crater  making  force 
is  centered  on  one  carbon.  It  is  even  true,  as  I  have  already 
said,  that  both  A.  C.  craters  combined  will  not  equal  the  area 
of  one  D.  C.  crater,  where  equal  amperage  is  used. 

It  has  long  since  been  very  generally  accepted  as  a  fact, 
however,  that,  due  to  optical  difficulties,  it  is  neither  feasible 
nor  good  practice  for  operators  projecting  with  A.  C.  to  use  both 
craters.  Operators  who  study  the  details  of  projection  have 
long  since  come  to  the  conclusion  that  a  more  uniformly  ex- 
cellent result  will  be  had  by  using  only  one  A.  C.  crater,  the 
upper,  of  course.  One  effect  which  almost  certainly  follows  an 
attempt  to  use  both  craters  is  a  double  spot  at  the  aperture, 


298  MOTION    PICTURE    HANDBOOK 

with  liability  to  produce  a  dark,  or  multicolored  streak  across 
the  center  of  the  screen.  This  is  due  to  the  fact  that  the  spot 
is  merely  an  image  of  the  crater  (see  Page  130),  and  with  two 
craters  there  will  be  two  images,  which  are  not  superimposed 
upon  each  other. 

For  years  an  effort  was  made  to  use  both  craters  by  means 
of  what  was  known  as  the  "jackknife"  set,  illustrated  at  B, 
Fig.  124,  and  A,  Fig.  124.  Some  also  attempted  to  utilize 
both  craters  by  setting  the  lamp  straight  up  and  down,  but 
these  schemes  have,  for  the  most  part,  been  relegated  to  the 
scrap  heap,  where  they  rightly  belong,  and  today  the  b  st 
men,  men  securing  the  best  results  and  holding  the  best 
positions,  almost  invariably  use  practically  exactly  the  same 
set  (illustrated  at  C,  Fig.  123,  and  in  Fig.  126),  both  for  A, 
C.  and  D.  C.,  or  else  use  a  very  modified  jackknife  set  by 
setting  the  lower  carbon  so  that  it  angles  out  very  moderate- 
ly with  relation  to  the  rackbars,  angling  the  top  carbon  to 
meet  it,  as  in  A,  Fig.  124.  Even  this  scheme  has,  however,  been 
largely  discarded  in  favor  of  the  regular  D.  C.  set.  Years 
ago  I  advised,  both  in  my  books  and  in  the  Projection  De- 
partment of  the  Moving  Picture  World,  the  use  of  the  same 
set  for  A.  C.  and  D.  C.  /  still  advise  it.  Theoretically,  setting 
the  lamp  straight  up  and  down  is  better;  practically,  however, 
it  is  not.  By  using  the  straight  up  and  down  lamp  set,  or  the 
jackknife  set,  one  is  enabled  to  get  considerably  higher  candle 
power  through  the  lens  for  a  given  amperage.  That  is  a  con- 
ceded fact,  but  the  fly  in  that  particular  box  of  ointment  is 
that  a  steady  light  absolutely  cannot  be  maintained  with  these 
sets,  or,  in  other  words,  the  curtain  illumination  cannot  he  held 
at  uniform  brilliancy.  I  cannot  recommend  either  the  setting 
of  the  lamp  and  carbons  perpendicularly,  the  jackknife  set, 
or  any  other  set  except  that  shown  in  Fig.  126,  Page  300, 
known  as  the  "regular  D.  C.  set." 

At  E,  Fig.  124,  we  see  the  result  of  carrying  an  alternat- 
ing current  arc  too  short — the  carbons  too  close  together. 
The  A.  C.  arc  is  very  short — much  shorter  than  the  D.  C., 
and  this  fault  must  be  carefully  guarded  against.  The  D.  C. 
current  arc  of  40  amperes  will  be  one-quarter  inch  to  three- 
eighth  inch  in  length;  the  A.  C.  arc  of  less  than  60  amperes 
will  not  be  much  in  excess  of  one-eighth  inch.  It  is  thus 
made  plain  that  the  operator  has  slight  leeway  in  handling 
the  A.  C.  arc.  It  must  be  watched  very  carefully,  fed  fre- 
quently, and  not  allowed  to  vary  from  normal  length.  The 
condition  shown  at  C,  Fig.  124,  is  as  good  as  you  can  hope 
for  when  using  60  amperes  or  less.  It  can  only  be  obtained 


FOR    MANAGERS    AND    OPERATORS 


299 


Figure  125. 


by    very    careful    adjust-         A  b 

ment  of  the  carbons, 
and  maintained  by  exer- 
cising watchful  care.  D 
shows  a  condition  Where 
the  lower  carbon  tip  has 
been  advanced  a  little 
too  much  with  relation 
to  the  upper  one,  so  that 
the  front  edge  of  the 
lower  crater  is  built  up 
until  it  shuts  off  a  large 
portion  of  the  light  em- 
anating from!  the  upper 
crater.  This  condition, 
too,  must  be  carefully 
guarded  against.  The 
only  remedy  for  condi- 
tion E,  Fig.  124,  is  to 
burn  a  long  arc  until  the 
saw  teeth  are  burned  off. 
The  only  remedy  for 
condition  D,  Fig.  124,  is 
to  alter  the  relation  of 
the  carbons  by  shoving 
the  top  carbon  tip  ahead 
slightly,  or  pulling  the 
lower  one  back. 

When  using  D.  C.  the 
careless  operator  who 
allows  his  arc  to  become 
too  short  may  find  the 
tip  of  his  lower  carbon 
crowned  with  a  sort  of 
mushroom — a  cap  having 
a  slim  stem.  This  cap 
is  composed  of  graphite. 
It  is  caused  by  keeping 
the  carbons  too  close 
together,  so  that  the 
arc  does  not  get  sufficient 

air  properly  to  volatize  the  carbon.  Under  these  conditions 
the  carbon  particles  carried  from  the  crater  are  deposited 
on  the  top  of  the  negative  carbon  in  the  form  of  graphite. 
Graphite  has  high  resistance,  and  will  withstand  enormous 


300  MOTION    PICTURE    HANDBOOK 

temperature  for  a  long  time.  Therefore,  this  cap  or  mush- 
room is  consumed  very  slowly.  The  remedy  is  to  knock  it 
off  with  a  screw-driver  having  an  insulated  handle,  and  to 
be  careful  not  to  again  allow  the  arc  to  get  so  short. 

Side-Lining  the  Carbons. — It  is  essential  that  the  upper 
and  lower  carbons  set  exactly  straight  with  each  other, 
viewed  from  the  front — that  is  to  say,  through  the  condensing 
lens  opening,  as  per  A,  Fig.  125,  in  which  A  shows  correct 
lining;  B,  top  carbon  out  of  line  and  C  both  out  of  line. 

Modern  lamps  have  an  adjustment  by  which  the  carbon 
tips  may  be  lined  with  each  other  sidewise,  but  if  the  upper 
and  lower  carbons  be  not  in  line  with  each  other  throughout 
their  length  then  as  they  burn  away  a  constant  sidewise 
adjustment  of  the  carbons  will  be  necessary  to  keep;  the 
crater  from  moving  over  to  one  side. 

When    the    operator    takes 
charge  of   a  plant,   or   when 

^gjjjjijjajk  a  new  outfit  is  purchased,  he 

should  put  in  two  carbons  of 
equal     diameter,     line     their 

Hfc  tips     exactly     sidewise     and 

wR  then,    with    a    straight    edge 

wk  laid  against  the  side  of  the 

•b  two    carbons,   test   them    for 

Ik  side   line.      If   either   carbon 

Rk  is    out    of    perpendicular    he 

W|  should  carefully  file  the  car- 

bon   clamp    until    the   matter 
^L.  is  remedied.  It  is  no  uncom- 

^k  mon  thing  to  find  lamps  with 

|^^^^  W|  either    the    upper    or    lower 

H|  Hk  carbon,  or  perhaps  both,  out 

^L       ...  Hi  of     plumb     sidewise.      With 

8k  Vk  some  lamps  it  is  possible  to 

9L  •  remedy       this       matter       by 

jlL  loosening   the    screws    which 

HL^^jjH  hold    the    carbon    arm    and 

shifting  the  arm   slightly. 

.JBHHKl-JLSL.  At    Fig.    126    is    a    photo- 

graphic representation  of  the 

Figure  126.  set  which  I  strongly  recom- 

mend for  both  D.  C.  and  A.  C. 

In  closing  the  subject  of  carbons  let  me  impress  upon  your 
minds  as  strongly  as  possible  the  following: 


FOR    MANAGERS   AND    OPERATORS  301 

Only  the  best  possible  results  from  a  given  amperage  can  be 
had  when  the  crater  is  in  precisely  the  right  position  with  rela- 
tion to  the  lenses,  with  the  least  possible  interference  by  the 
lower  carbon  tip,  and  this  condition  can  only  be  obtained  by  a 
very  careful  adjustment  and  setting  of  your  carbons. 

Some  interesting  data  and  information  may  be  found  in  the 
following  tabulated  results  of  experiments  made  by  the 
editor. 

SET:  FIVE-EIGHTH  INCH  CORED  ABOVE  AND 

BELOW. 

Current  Through  G.  E.  50  Ampere  Mercury  Arc   Rectifier 
on  Lowest  Notch. 

Approximate     distance     between 

carbon    tips  at   their  nearest  Voltage  at 

point.  Arc.  Amperage. 

1/16"  40  33 

1/16"  45  28 

3/32"  50  2S*/2 

1/8  "  55  22y2 

3/16"  60  20 

1/4  "  Arc  unstable.  65 

5/16"  Arc  very  unstable.  70  15 

75  Arc  went  out. 


SET:  FIVE-EIGHTH  INCH  CORED  ABOVE  AND  THE 
SAME  SIZE  SOLID  BELOW. 

Approximate     distance     between 
carbon  tips   at  their  nearest  Voltage  at 

point.  Arc.  Amperage. 

1/32"                                                40  31 

3/32"                                                 45  2?y2 

3/16"                                                50  24*/2 

1/4  "                                                 55  22^ 
5/16"                                                60 
3/8  "    7/16"                                    65 

70  Arc  very    unstable 

and  went  out  after 

five  seconds. 

It  was  observed  that  with  two  new  five-eighth  inch  cored 
carbons,  in  order  to  keep  the  arc  voltage  down  to  50,  and 
thus  keep  the  amperage  within  reasonable  bounds,  it  was 
necessary  to  separate  the  carbons  \%  inches  for  the  first  15 
to  30  seconds,  after  which  the  arc  resistance  gradually  but 
rapidly  rose,  until  a  50  volt,  25  ampere  arc  was  had  with  as 
little  as  three-thirty-second  inch  separation  at  the  nearest 


302 


MOTION    PICTURE    HANDBOOK 


point  of  contact  between  the  lower  tip  and  the  crater  on 
the  upper  carbon. 

With  a  new  set  of  the  same  size  carbons,  but  with  cored 
above  and  solid  below,  the  extreme  distance  was  reduced  from 
1/4  inch  to  1  inch,  and  the  arc  voltage  reduced  to  normal 
much  earlier  than  with  two  cored. 

After  striking  an  arc  with  two  new  five-eighth  inch  cored, 
burning  it  20  seconds,  breaking  it  long  enough  to  measure 
distance  between  tips,  and  relighting,  with  30  volts  across 
the  arc  there  was  still  50  amperes,  and  the  arc  was  still 
abnormally  long.  Under  similar  conditions,  with  two  cored 
and  the  arc  voltage  at  40,  amperage  stood  at  only  30. 

All  this  has  some  value  in  that  it  shows  a  less  tendency 
to  heavy  current  rush  on  new  sets  when  a  solid  is  used 
below. 

Carbon  Economizers. — There  are  now  on  the  market  a 
number  of  good  carbon  economizers,  ranging  in  price  from 
50  cents  to  $1  which  may  be  had  from  supply  dealers.  These 
devices  are  designed  to  allow  the  operator  to 'consume  his 
carbon  stubs  down  to  the  shortest  possible  length.  Some 
are  made  of  brass,  and  some  of  iron.  'They  are  simple  and 
quite  effective. 

Lighting  Interior  of  Lamphouse. — It  would  be  a  very 
simple  matter  to  place  a  small  porcelain  lamp  receptacle 

in     the     bottom     of     the 
lamphouse,    at    the    right 
hand,  front  corner.    From 
one  side  run  a  wire  to  one 
side     of     any    convenient 
%      incandescent  circuit.  From 
-o  the  other  side  attach  to  the 
~£   other   side  of   the   circuit 
through    a    spring-switch, 
-£    made  as  per  Fig.  127,  at- 
tached  to  the  right  hand 
lamphouse    wall    in    such 
way  that  a  piece  of  fibre 
fastened  to  the  lamphouse 


Figure  127. 


door   will   shove   the   switch    open,   thus   putting  out   the  light, 
when  the  lamphouse  door  is  closed. 

By  the  use  of  a  low  C.  P.  lamp  the  interior  of  the  lamp- 
house 'is  thus  automatically  illuminated  when  one  opens  the 
door  to  re-set  the  carbons,  etc. 


FOR    MANAGERS   AND    OPERATORS  303 

Arc  Controller 

WHILE   the   Arc  Controller  is   a   new  invention   it   has 
been    in   use   long   enough    to    thoroughly   prove   its 
practicability  and  utility;  also  it  carries  with  it  the 
indorsement  of  the  Projection  Department  of  the  Moving  Pic- 
ture World. 

The  function  of  the  controller  is  automatically  to  feed  the 
carbons  of  the  arc  lamp.  Its  method  of  accomplishing  this 
is  quite  simple  and  thoroughly  positive. 


Plate  1,  Figure  128. 

Broadly  speaking,  the  amperage  of  the  arc  is  regulated  by 
the  voltage  of  the  arc,  and  no  matter  whether  current  be 
taken  through  a  rheostat,  directly  from  a  generator,  or 
through  a  transformer,  any  change  in  voltage  across  the  arc 
will  cause  corresponding  change  in  amperage  at  the  arc.  If  the 
voltage  rises  the  amperage  drops;  if  the  voltage  drops,  the 
amperage  rises.  This  is  what  may  be  termed  the  immutable 
law  of  the  electric  arc. 


304  MOTION    PICTURE    HANDBOOK 

The  Arc  Controller  operates  as  follows:  In  P.  1,  A  is  a 
small  motor  which  drives  the  mechanism  of  controller  B, 
illustrated  in  P.  3.  Controller  B,  P.  1,  is  connected  to  the  arc 
lamp  by  means  of  rod  2,  P.  1  and  2,  this  rod  being  driven  by 
gear  44,  P.  3.  By  tracing  through  the  connection  you  will 
see  that  motor  A  is  thus  positively  and  directly  connected 
to  rod  1,  P.  2,  which  is  commonly  known  as  the  "feed 
handle"  of  the  arc  lamp— the  handle  by  means  of  which  the 
carbons  are  fed  together.  Motor  A,  P.  1,  is  connected  to 
the  line  by  means  of  wires  contained  in  cable  9,  P.  1,  the 
other  end  of  which  is  seen  at  7,  P.  1,  where  it  joins  the 
fuse  box.  The  motor  is  not  connected  directly  to  the 
supply  line,  but  to  the  projection  machine  table  switch 
contacts,  through  cables  8,  P.  1,  which  are  controlled  by 
switch  5,  P.  1.  It  will  thus  be  seen  that  motor  A  does 
not  receive  the  full  line  voltage,  but  only  the  arc  voltage, 
which  varies  with  the  length  of  the  arc.  Now,  even  the 
novice  will  understand  that  the  speed  of  motor  A  will  depend 
upon  the  voltage  of  the  current  with  which  it  is  supplied, 
hence,  any  rise  in  arc  voltage,  no  matter  how  small,  will  in- 
crease the  motor's  speed. 

Referring  to  P.  2,  knurled  knob  12  passes  through  fibre 
disc  9,  through  the  end  of  brass  lever  16,  and  impinges  on 
the  surface  of  fibre  disc  8. 

Brass  lever  16  is  hinged  to  a  steel  collar,  which  passes 
over  and  is  attached  to  feed  rod  1,  P.  2.  Now,  when  knurled 
knob  12  is  backed  off  (unscrewed  somewhat),  it  has  the 
effect  of  unlocking  fibre  disc  8  and  driving  gear  4,  from 
fibre  disc  9  and  feed  rod  1.  In  other  words,  when  knob  12 
is  loosened,  or  backed  off,  the  lamp  becomes  a  plain  hand- 
fed  lamp,  of  which  fibre  disc  wheel  9  is  the  feeding  knob  or 
wheel,  and  the  motor  is  allowed  to  drive  gear  4  and  fibre 
disc  8,  without  moving  rod  1,  P.  2.  Conversely,  when  knurled 
knob  12  is  screwed  in  the  whole  thing  is  locked  together,  and 
the  motor  then  drives  lamp  feed  rod  1,  P.  2,  direct,  by  means 
of  gear  6  acting  on  gear  4,  thus  feeding  the  carbons  of  the 
lamp  together.  To  make  matters  still  more  clear,  gear  4  and 
fibre  disc  8  merely  use  rod  1  as  an  axle.  They  are  entirely 
independent  of  disc  9  and  rod  1,  except  when  locked  to  them 
by  knurled  knob  12.  When  not  so  locked,  gear  4  and  disc 
8  can  rotate  without  in  any  way  affecting  disc  9  and  rod  1. 
The  operation  of  the  device  is  as  follows:  When  the  operator 
is  ready  to  strike  his  arc,  he  closes  switch  5,  P.  1,  which 
starts  motor  A  running,  but  it  is  only  driving  fibre  disc  8 
and  gear  4,  P.  2.  The  operator  now  strikes  his  arc  by  means 


FOR    MANAGERS   AND    OPERATORS 


305 


of  the  hand  feed  (disc  9,  P.  2),  in  the  usual  way,  adjusts  it 
at  approximately  the  right  length,  and  then  screws  in  knurled 
knob  12,  which  locks  the  mechanism  together,  and  thereafter 
he  theoretically  need  give  the  arc  no  further  attention  what- 
ever. 
You  will  observe  I  said  "theoretically";  this  by  reason  of 


Plate  2,  Figure  129. 

the  fact  that  faults  in  the  carbon  and  things  of  the  sort  may 
make  it  necessary  occasionally  to  work  the  hand  feed.  As 
a  general  proposition,  however,  the  controller  takes  care  of 
the  entire  situation,  so  far  as  feeding  of  the  carbons  be  con- 
cerned, and  I  have  myself  seen  a  full  show  of  eight  reels  run 
without  the  operator  at  any  time  touching  the  arc  lamp,  ex- 


306 


MOTION    PICTURE    HANDBOOK 


cept  to  strike  and  set  the  arc  at  the  beginning  of  each  reel. 
The  controller  maintains  a  perfectly  steady  arc  voltage, 
hence  a  perfectly  steady  arc  amperage  and  even  light  density. 

The  Controller. — P.  3  is  an  interior  view  of  controller  B, 
P.  1,  with  cap  1,  P.  1,  removed.  In  this  view  gear  10  is  the 
gear  which  meshes  with  gear  44,  P.  3,  which  drives  rod  2,  P.  1. 
Now  follow  me  closely:  Spring  41,  P.  3,  is  attached  to  pawl  23 
by  slipping  bend  42  into  the  eyehole  at  22  of  part  23,  P.  3. 


Plate  3,  Figure  130. 

This  has  the  effect,  when  cover  40  is  in  place,  of  holding 
part  23  back,  in  the  direction  of  the  arrow  point  34.  Parts 
28-28  are  governor  weights  attached  to  governor  cross  bar 
27  by  means  of  hinge  pin  47  and  35,  and  right  here  is  what 
might  be  termed  the  heart  of  the  whole  machine.  Part  3? 
swivels  upon  part  32  and  the  whole  governor  is  attached  to 
the  main  driving  shaft  by  pin  38  in  part  27.  Part  31  is  a 
steel  tooth  driven  through  part  23,  and  protruding  about 
one-eighth  inch  on  the  side  next  to  wheel  16.  All  the  parts 
between  part  27l/2,  which  is  a  ball  bearing,  and  part  26,  an- 


FOR    MANAGERS   AND    OPERATORS  307 

other  ball  bearing,  which  includes  the  entire  governor, 
revolve  at  the  speed  of  the  motor,  and  weights  28-28  are 
held  normally  in,  by  means  of  spring  41  which  holds  part 
23  back  against  ball  bearing  26,  which  in  turn  presses  back 
part  32,  carrying  pins  25,  which  bear  on  the  inner  end  of  the 
arm  carrying  weights  28-28.  Before  going  any  further  study 
this  action  closely,  and  get  it  firmly  fixed  in  your  mind. 

Now  here  is  how  the  thing  operates.  The  motor  runs 
constantly,  but  its  speed  increases  as  the  length  of  the  arc 
increases,  because  the  voltage  increases  with  length  of  arc, 
and  as  a  result  of  the  increased  motor  speed,  governor 
weights  28-28  are  thrown  outward  against  the  pull  of  spring 
41,  which  has  the  effect  of  forcing  part  32,  ball  bearing  26 
and  part  23  ahead,  thus  engaging  tooth  31  with  one  of  stop 
teeth  15  on  wheel  16. 

Gears  14-17-29  form  a  "differential,"  gear  29  being  attached 
to  wheel  16,  gear  14  to  shaft  19  (by  means  of  pin  13),  and  gear 
17  to  gear  18.  Underneath  gear  18  is  a  worm  gear  attached 
to  the  shaft  connecting  the  controller  to  the  motor — the  main 
driving  shaft.  This  worm  gear  drives  worm  gear  18,  mounted 
and  riding  loosely  on  shaft  19.  When  the  motor  is  running, 
but  the  arc  is  not  being  fed,  the  motor  continues  to  drive 
gear  18,  but,  wheel  16  being  free  to  turn,  the  differential  acts 
and  gear  29  simply  runs  around  on  gear  13,  without  oper- 
ating gear  10.  A  moment's  study  will,  I  think,  enable  you 
to  understand  this  action.  It  is  very  similar  to  the  action  of 
the  differential  of  an  automoble.  Gear  29  must  rotate  gear 
10,  which  in  turn  drives  gear  44  and  rod  2,  P.  1  and  2,  and 
through  it  lamp  feed  handle  1,  P.  2,  thus  feeding  the  lamp 
carbons  together,  shortening  the  arc  and  reducing  the  voltage 
so  that  the  motor  slows  up,  whereupon  spring  41  overcomes 
the  lessened  centrifugal  force  acting  on  weights  28-28,  so 
that  they  are  pulled  inward,  which  disengages  tooth  31  from 
tooth  15,  which  causes  the  differential  to  act  and  the  carbons 
are  no  longer  fed. 

The  speed  necessary  to  cause  tooth  31  to  engage  tooth  15 
will  depend  entirely  upon  the  tension  of  spring  41,  which  is 
regulated  by  nut  46  on  bolt  45,  P.  3,  (3,  P.  1),  and  this  tension 
must  be  adjusted  by  the  operator  as  soon  as  he  has  the  con- 
troller connected  up,  as  will  be  hereinafter  explained. 

Oil. — The  well  formed  by  the  gear  casing  should  be  kept 
filled  with  a  good  grade  of  dynamo  oil.  Oil  is  poured  in 
through  oil  well  14,  P.  1,  and  it  should  reach  the  level  of  the  top 
of  the  spout.  One  filling  of  good  lubricant  ought  to  last  about 


308  MOTION    PICTURE    HANDBOOK 

500  running  hours.  Before  refilling,  remove  the  plug  in  the 
opposite  end  of  14,  P.  1,  drain  out  all  the  old  oil,  replace  the 
plug,  fill  the  well  with  kerosene  and  let  the  machine  run  for 
a  few  minutes;  drain  the  kerosene  out  and  then  refill  with 
clean  oil. 


\ 


/*>.?  tf.^f 


*T"r»~rv~r    iv,<v*- 


\ 


Plate  4,  Figure  131. 

Caution: — You  are  cautioned  against  the  use  of  the  very 
thin,  much  advertised  oils.  They  are  totally  unfit  for  use  on 
such  machines  as  this.  The  manufacturers  of  the  controller  rec- 
ommend Solar  Red  Oil.  I  do  not  personally  know  anything 
about  this  lubricant,  but  presume  it  is  good.  In  any  event, 
however,  a  good  grade  of  dynamo  oil  will  serve  the  purpose. 
If  the  Solar  Red  Oil  can  be  had,  use  it;  if  not,  use  the  other, 
which  you  can  no  doubt  obtain  from  your  local  electric  light 
company,  or  from  any  reliable  oil  dealer. 

Connecting  the  Machine. — When  a  controller  is  received  and 
unpacked,  examine  the  packing  carefully,  making  sure  that  no 
small  parts  are  thrown  away.  Also  remember  that  the  manu- 
facturer will  not  recognize  claims  for  shortage  unless  made 
immediately  after  receipt  of  the  machine.  The  apparatus  will  con- 
sist of  the  following:  (a)  The  controller  and  motor,  con- 
nected in  one  unit,  as  shown  in  the  lower1  half  of  P.  1, 
including  cables  7,  8,  9  and  the  fuse  box  as  shown  in  P.  1. 
All  this  will  be  found  coupled  together  when  received:  (b) 
telescope  rod  2,  P.  1  and  2,  consisting  of  a  steel  rod  inside 
a  brass  tube;  (c)  collar  \l/2,  part  3,  including  gear  6,  fork  7 
and  universal  joints  13,  P.  2;  (d)  gear  4,  fibre  knobs  8  and  9 
and  part  16. 

After  unpacking  and  inspecting  the  parts  proceed  as  fol- 
lows: First  set  the  controller  and  motor,  B-A,  P.  1,  on  the 
floor  immediately  under  the  feed  rod  handle  of  the  arc  lamp. 
It  may  be  set  on  a  block  high  enough  to  raise  it  out  of  the 
dirt — say  3  to  6  inches,  if  desired.  If  necessary  the  controller 
may  be  set  a  little  to  one  side,  or  a  little  back,  if  the  conduit 
carrying  the  lamp  leads  is  in  the  way.  Within  the  limits 


FOR  MANAGERS  AND  OPERATORS 


309 


of  the  reach  of  telescopic  rod  2-2,  P.  1  and  2,  the  position  of 
the  controller  may  be  changed    The  idea  is  shown  in  P.  7. 

Caution: — In  this  connection  be  very  careful  not  to  get 
the  controller  so  far  away  from  a  position  underneath  the 
lamp  feed  handle  that  universal  joint  4,  P.  1,  and  the  univer- 
sal joint  13,  P.  2,  will  be  at  too  great  an  angle  and  bind.  It 
is  hardly  probable  that  you  would  do  this,  but  it  is  never- 
theless possible,  and  must  be  guarded  against. 


* 


)  C) 


O 


O  () 


tt 


& 


Plate  5,  Figure  132. 

Having  placed  the  controller,  next  take  off  the  feed  wheel, 
or  knob,  from  the  rod  which  feeds  the  carbons  of  your  lamp, 
and  slip  collar  1J4,  P.  2,  on  the  rod.  Now,  take  part  3,  carry- 
ing gear  6  and  fork  7,  in  your  left  hand,  and  gear  4  and  fibre 
knobs  8  and  9  in  your  right  hand,  and  fit  them  together  so 
that  gear  6  meshes  properly  with  gear  4,  and  the  hole  through 
the  hollow  stem,  18,  P.  2,  is  clear,  except  for  the  pin  passing 
through  it.  Having  fitted  the  parts  together  in  your  hand, 
slip  the  whole  on  rod  1,  first  having  removed  knob  17,  P.  2, 
or  the  knob  of  some  other  rod  which  conies  most  directly 
under  rod  1,  and  make  fork  7  straddle  the  rod;  after  which 
knob  17  should  be  replaced.  It  may  not  be  necessary  to 
remove  knob  17.  Very  likely  you  can  get  the  fork  over  the 
rod  without.  The  reason  for  fork  7  straddling  one  of  these 
rods  is  to  prevent  part  3  from  turning — to  hold  it  stationary. 


310 


MOTION    PICTURE    HANDBOOK 


Slip  these  parts  on  rod  1  until  its  end  strikes  the  pin  which 
you  will  see  in  hole  18,  about  one-half  inch  from  the  surface 
of  the  fibre  knob.  This  pin  must  not  be  removed.  If  the 
parts  do  not  go  on  the  rod  easily  do  not  try  to  force  them 
but  find  out  what  is  wrong  and  remedy  it.  Having  accom- 
plished this,  tighten  up  set  screw  15,  P.  2,  good  and  tight. 
Bring  back  collar  ll/2  to  about  the  thickness  of  a  postal  card 
from  the  sleeve  inside  part  3,  and  tighten  its  set  screw. 

Now  all  you  have  to  do  is  to  connect  rod  2,  P.  1  and  4  with 
universal  joints  4,  P.  1,  and  13,  P.  2,  and  remove  the  wooden 
plug  from  the  cover  of  the  controller.  Its  use  is  to  preserve 


Plate  6,  Figure  133. 

in  transit  the  oil  with  which  the  controller  is  filled.  The  hole 
that  it  protected  is  a  "breather,"  and  must  be  left  open  when 
the  controller  is  in  operation. 

If  gear  6,  P.  2,  does  not  incline  at  the  proper  angle  to  clear 
rod  2  from  any  obstruction,  loosen  a  screw  on  the  right  side 
of  part  3  and,  with  knurled  knob  12  loosened,  turn  gears  6 
and  4  and  fibre  knob  8  to  the  desired  angle.  Then  tighten  the 
screw  in  part  3  very  tightly.  This  completes  the  mechanical 
installation. 

Electrical  Connections. — First  if  your  current  is  D.  C.  see 
to  it  that  your  rheostat  is  placed  in  the  positive  wire  (the 
wire  leading  to  the  upper  carbon),  and  between  the  machine 

table  (operating)  switch  and  the  lamp.  //  it  is  on  the  negative 
wire  change  it  to  the  positive,  and  then  if  the  current  is  110  or 


FOR    MANAGERS    AND    OPERATORS 


311 


115  volts  make  your  connections  as  per  P.  4,  in  which  A  is 
the  switch-box,  shown  photographically  in  P.  1,  and  dia- 
grammatically  in  P.  5.  On  the  leads  from  switch-box  A  will 
be  found  tags  reading  respectively  "field,"  "line,"  "armature," 
the  field  and  line  wires  being  in  the  same  B-X  conduit.  The 
field  wire  must  be  connected  to  the  positive  pole  of  the  ma- 
chine table  or  operating  switch,  on  its  dead  side,  at  B,  P.  4.  The 


Plate  7,  Figure  134. 

line  wire  must  be  connected  to  the  opposite  pole,  at  C,  P.  4. 
The  armature  wire,  which  is  asbestos  covered,  must  be  con- 
nected to  the  positive  asbestos  covered  lamp  lead  (one  leading 
to  upper  carbon),  between  the  rheostat  and  lamp,  as  per  P. 
4.  This  may  be  done  by  removing  the  insulation  of  the  lamp 
lead  for  an  inch  or  so,  scraping  the  wire  strands  and  the  end  of 
the  armature  wire  perfectly  clean,  wrapping  the  end  of  the 
armature  wire  tightly  around  the  lamp  lead  and  soldering 
the  joint,  after  which  the  joint  must  be  wrapped  with  in- 
insulating  tape.  It  is  VERY  IMPORTANT  that  all  the  electrical  con- 
nections be  perfectly  tight. 


312  MOTION    PICTURE    HANDBOOK 

P.  5  shows  the  wiring  of  switch-box  A,  P.  4,  and  6,  P.  1. 
The  B-X  conduit  joining  the  switch-box  and  the  motor  A, 
P.  1,  contains  three  No.  14  wires,  each  having  a  different 
colored  insulation,  one  red,  one  white  and  one  black.  The 
red  is  the  field  wire  which  connects  through  the  switch-box, 
to  B,  P.  4;  the  white  wire  is  the  line  which  connects  at  C, 
P.  4,  and  the  black  the  armature,  which  emerges  from  the 
switch-box  as  an  asbestos  covered  wire.  The  connections 
are  perfectly  plain  when  you,  in  your  mind,  substitute  P.  5 
for  switch-box  A,  P.  4. 

Caution. — Be  very  sure  that  your  rheostat  is  located  on  the 
POSITIVE  wire  and  BETWEEN  THE  MACHINE  TABLE  OR  OPERATING 
SWITCH  AND  THE  LAMP.  If  it  is  on  the  other  (line  side)  of  the 
machine  table  switch,  change  it,  since  otherwise  the  con- 
troller would  not  work. 

It  is,  however,  possible  to  have  the  rheostat  in  the  nega- 
tive wire  or  on  the  other  side  of  the  operating  switch  by 
using  different  wiring  diagrams,  and  the  manufacturers  pro- 
vide for  this  if  notified,  but  the  simplest  way  is  to  use  one 
diagram  and  change  the  position  of  your  rheostat  if  neces- 
sary. 

When  using  converted  alternating  current,  through  a  motor 
generator  set,  rotary  converter,  or  mercury  arc  rectifier, 
or  where  D.  C.  voltage  is  reduced  by  D.  C.  to  D.  C.  econ- 
omizer, the  wiring  diagram  as  per  P.  6  must  be  used,  though 
it  applies  to  no  other  condition. 

In  ordering  the  controller  you  should  send  an  exact  dia- 
gram of  your  wiring,  decribe,  in  detail,  the  various  apparatus 
used,  and  give  the  kind  of  current  and  its  voltage,  and,  if  A. 
C.,  the  cycle.  In  using  diagram,  P.  6,  if  there  is  an  arrange- 
ment for  switching  over  to  A.  C.  in  case  of  failure  of  con- 
verting apparatus,  then  the  controller  connections  must  be  on  the 
converter  side  of  a  double-throw  switch  which  will  cut  it  out 
of  service  when  A.  C.  is  used,  because  under  no  circumstances 
must  the  controller  be  subjected  to  alternating  current,  or  any 
voltage  higher  than  115. 

Operation. — The  controller  will  maintain  the  length  of  arc 
for  which  it  is  adjusted,  and  the  length  of  the  arc  is  altered 
by  tightening  or  loosening  nut  46,  P.  3.  After  the  controller 
has  been  connected  up  and  put  into  operation,  if  the  arc  is 
too  short,  tighten  up  on  this  nut;  if  it  is  too  long  loosen  it 
until  the  desired  length  is  attached.  Examine  the  oil  cups  of 
the  motor  once  a  week  and  fill  them  up.  Examine  the  com- 
mutator of  the  motor  occasionally. 


FOR   MANAGERS   AND    OPERATORS  313 

Should  anything  go  wrong  with  the  internal  gearing  of  the 
controller  it  will  be  necessary  that  it  be  returned  to  the  factory 
for  adjustment.  It  is  not  advisable  to  try  to  repair  the  con- 
troller yourself,  but,  on  the  other  hand,  it  is  extremely  im- 
probable that  anything  will  go  wrong. 

Use  only  motor  brushes  supplied  by  the  manufacturers. 
The  motor  brushes  may  be  removed  by  unscrewing  their 
brass  retaining  disc,  but  in  replacing  be  sure  they  are  exactly 
in  the  position  from  which  they  were  withdrawn.  The 
manufacturers  show  one  pencil  mark  on  the  top  of  the  left-hand 
brush  and  two  pencil  marks  on  the  top  of  the  right-hand  brush  to 
indicate  their  correct  positions.  The  box  in  the  top  of  the 
motor  is  merely  a  junction  box  in  which  the  leads  from  the 
motor  are  soldered  to  those  in  the  B-X  leading  therefrom. 


ASBESTOS    COVERED   LAMP   LEADS 

The  connection  between  the  machine  table  switch  and  the 
arc  lamp  and  between  the  machine  table  switch  and  the 
rheostat  invariably  is  made  with  what  is  called  asbestos- 
covered  strand  wire,  this  by  reason  of  the  fact  it  must  be 
quite  flexible;  also,  its  insulation  must  withstand  consider- 
able heat. 

Following  the  recommendations  of  the  Projection  Depart- 
ment! of  the  Moving  Picture  World  and  the  Handbook  the 
general  practice  is  to  use  No.  6  asbestos  wire,  and  this  size 
is  ample  for  ordinary  work.  However,  everything  con- 
sidered, I  believe  that  in  houses  where  high  amperage  is 
used  it  would  be  good  practice,  and  true  economy  in  the  end, 
to  use  No.  5  instead  of  No.  6  abestos  wire.  No.  6  is  more 
than  capable  of  carrying  the  current,  it  is  true,  but  portions 
of  it  are  subjected  to  pretty  high  temperature,  so  that,  on  the 
whole,  while  granting  that  No.  6  will  answer,  I  believe  No. 

5  would  be  still  better. 

Before  asbestos  strand  wire  is  purchased  a  sample,  which 
may  be  only  half  an  inch  long,  should  first  be  secured  and  the 
diameter  of  a  few  of  the  strands,  picked  out  at  random, 
carefully  measured  in  thousandths  of  an  inch,  with  a  mi- 
crometer caliper.  Having  done  this  you  can  look  at  Table 

6  and    see    what    number   of   wire    the    strands    are.      Next 
multiply   the    diameter   by   itself,   which    will    give    you   the 
C.  M.  cross-section;  count  the  number  of  strands  in  the  wire, 
and  multiply  the  area  of  one  strand  by  the  total  number  of 
strands,  which  will   give   you   the  total   C.   M.   cross-section 


314 


MOTION    PICTURE    HANDBOOK 


of  the  sample.  Compare  this  with  area  of  the  wire  it  is 
supposed  to  be  and  if  there  is  a  discrepancy  on  the  wrong 
side  don't  buy  the  wire,  but  demand  one  having  such  number 
of  strands  that  their  combined  cross-section  will  equal  the 
cross-section  of  this  size  wire  you  want.  This  is  important, 
because  many  manufacturers  of  stranded  wire,  depending 
upon  the  carelessness  or  ignorance  of  the  purchaser,  hold 
out  from  five  to  ten  strands.  Only  a  vigorous,  combined 
kick  will  stop  this  practice. 

Operators  should  watch  their  asbestos  wire  closely,  and  as 
soon  as  that  portion  inside  the  lamphouse  begins  to  feel 
"soft"  and  pliable,  without  any  spring  to  it,  the  end  should 
be  cut  off  and  thrown  away,  since  it  has  high  resistance,  and 
in  a  day's  run  will  waste  more  power  than  it  is  worth.  See 
Page  233  for  a  suggestion  on  this  latter. 

TABLE  6. 
Diameter  of  Small  Wires. 


B.  &  S.  Gauge. 

Diameter  in  Decimal 
Fractions  of  an  Inch. 

Diameter  in  Mills. 

21 

.028462 

28. 

22 

.025347 

25. 

23 

.022571 

22.5 

24 

.020100 

20. 

25 

.017900 

18. 

26 

.015940 

16. 

27 

.014195 

14. 

28 

.012641 

12.5 

29 

.011257 

11.2S 

30 

.010025 

10. 

31 

.008928 

9. 

32 

.007950 

8. 

33 

.007080 

7. 

34 

.006305 

6. 

35 

.005615 

5.6 

Note:     Mill   diameter   is  not   exact. 


FOR   MANAGERS   AND    OPERATORS  315 

Toledo  Non-Rewind 

THE  Toledo  non-rewind  includes  an  aluminum  cast  maga- 
zine, 5  inches  deep  by  approximately  16  inches  in  diameter, 
upon  the  back  of  which  is  mounted  an  intermittently  run- 
ning   motor    which    drives    a    mechanism    carrying    reel    A, 
plate    1.    This    reel    is    specially    designed.     Its    hub    is    col- 
lapsible, being  controlled  by  lever  1  and'  spring  2.     Mounted 


Plate  1,  Figure  135. 

on  a  circular  metal  plate  3,  to  which  the  reel  is  attached 
when  in  the  magazine,  is  a  collapsible  metal  band,  not 
visible  in  the  photograph  but  controlled  by  knob  4,  P.  1. 
The  operation  is  essentially  as  follows: 

When  the  reel  is  received  from  the  exchange  it  is  placed 
in  the  magazine   on  an   extension  to   spindle  5,   and  the  mag- 


316 


MOTION    PICTURE    HANDBOOK 


azine  is,  by  a  suitable  mechanism,  shown  at  X  in  P.  2,  re- 
leased and  swung  half  way  around,  whereupon  the  film  may 
be  threaded  through  the  magazine  the  same  as  it  would  be 
were  the  regular  upper  magazine  in  use,  a  non-rewind  reel 
meanwhile  having  been  placed  in  the  lower  magazine  to 
receive  the  film.  After  the  film  is  wound  on  the  non-rewind 


Plate  2,  Figure  136. 

reel  the  operation  from  then  on  is  simple.  The  non-rewind 
reel  is  placed  in  the  upper  magazine,  and  the  mechanism 
is,  by  a  few  simple  moves,  adjusted,  locking  the  reel  to  the 
back  plate  which  is  driven  by  the  motor  on  the  back  of  the 
magazine,  P.  2.  After  locking  the  reel  into  place,  the  col- 
lapsible band  is,  by  the  movement  of  a  lever,  brought  down 


FOR    MANAGERS    AND    OPERATORS 


317 


until  it  clamps  the  outer  circumference  of  the  film.  This 
band  expands  and  contracts  in  a  true  circle,  and  will  accom- 
modate a  reel  of  film  as  small  as  450  feet  or  as  large  as  1100 
feet. 

It  is  somewhat  difficult  to  describe  the  action  of  this 
machine  without  an  abundance  of  carefully  numbered  photo- 
graphs, which,  as  the  Toledo  was  only  placed  on  the  market 
at  about  the  time  this  book  was  ready  for  publication,  there 


Plate  3,  Figure  137. 

was  not  time  to  prepare.  However,  the  motor  shown  in  P.  2 
is  controlled  by  switch  B,  P.  2,  and  this  switch  in  turn  is 
actuated  by  a  roller  which  bears  upon  the  film  at  X,  P.  1. 
When  the  length  of  film  shown  in  P.  1  is  drawn  taut  this 
roller  is  shoved  back,  which  raises  switch  B,  P.  2,  thus  making 
electrical  contact  and  starting  the  motor.  When  the  motor 
is  running,  the  reel  in  the  upper  magazine  is  revolved,  which 
has  the  effect  of  releasing  a  portion  of  the  film  and  literally 
shoving  it  out  of  the  reel.  The  instant  this  is  done,  the 


318  MOTION    PICTURE    HANDBOOK 

length  of  film  shown  in  plate  1  slacks,  which  lets  the  roller 
go  forward,  thus  opening  switch  B,  P.  2.  As  a  matter  of 
fact,  in  actual  operation  the  motor  starts  and  stops  about 
twice  every  second. 

As  will  be  seen  the  film  is  taken  from  the  center  of  the 
reel.  It  is  brought  out  across  an  angle  piece  and  comes 
down  through  a  firetrap,  into  the  mechanism,  through  which 
it  is  threaded  in  the  usual  way.  The  power  required,  so  far 
as  wattage  be  concerned,  is  almost  nothing.  It  would  prob- 
ably not  add  more  than  25  cents  to  the  current  bill  in  a  whole 
month,  if  it  does  that  much. 

P.  1  and  2  show  the  front  and  back  views,  and  P.  3  the 
magazine  turned  to  receive  the  exchange  reel  on  the  first 
run.  With  this  device  it  is  not  necessary  to  do  any  rewind- 
ing at  all. 


T 


Feaster  Non-Rewind  Machine 

HIS  device  is  a  highly  practical  mechanism  by  means 
of  which  the  rewinding  of  film  is  eliminated,  except 
•that  it  is  necessary  for  the  operator  in  the  first  place 


Plate  1,  Figure  138. 

to  wind  the  film  from  the  exchange  reel  to  a  special  reel, 
which  is  a  part  of  this  outfit.  It  can  be  attached  to  any 
machine  by  the  average  operator  in  just  a  few  minutes. 


FOR    MANAGERS   AND    OPERATORS  319 

The  magazines,  20-21,  Plate  1,  set  level,  regardless  of  the 
angle  at  which  the  projector  mechanism  may  set.  There 
are  few  parts  to  wear  out,  and  any  film  in  condition  to  go 


Plate  2,  Figure  139. 

through  a  projector  will  successfully  pass  through  the 
Feaster.  In  P.  1  and  2  the  device  is  seen  attached  to  a 
Power's  mechanism.  It  attaches  with  equal  facility  to  any 
standard  projection  machine. 

In  attaching  the  Feaster  to  a  Power's  machine  all  that  is 
necessary  is  to  remove  the  upper  magazine  and  replace  it 
with  the  Feaster,  -adjusting  it  with  thumb  screws  provided 
until  gear  7,  P.  1,  meshes  properly  with  the  gear  on  the  pro- 
jector. Whereupon  tighten  up  thumb  screws,  3,  P.  2,  and 
level  the  magazines  by  means  of  turn-buckle  16,  P.  2.  This 
whole  operation  should  not  consume  more  than  five  min- 
utes. Attachment  to  other  makes  of  machine  is  almost 
equally  simple.  The  added  complication  in  threading  amounts 
to  very  little. 

Plate  2  shows  the  method  of  placing  the  film  in  the 
magazine.  The  film  is  first  rewound  from  the  exchange 
reel  to  a  special  Fenston  reel,  enough  of  which  are  fur- 
nished to  carry  any  show.  One  side  of  the  reel  is  instantly 


320 


MOTION    PICTURE    HANDBOOK 


detachable.  The  threading  is  quite  simple  and  sprocket, 
41,  P.  3,  maintains  a  constant  supply  of  film  to  the  mechan- 
ism, between  Which  and  sprocket  41,  inside  the  magazine, 


Plate  3,  Figure  140. 

there  is  a  loop  as  per  P.  4.  P.  4  shows  the  internal  con- 
struction. Pan  31,  which  carries  the  film  roll,  rides  on 
steel  balls  (three  of  them),  52,  which  are  held  equidistant 
from  each  other  by  ring  32.  The  friction  is  thus  reduced 
to  a  negligible  quantity. 


FOR   MANAGERS   AND    OPERATORS 


321 


This  or  similar  machines  are  to  be  commended  for  several 
reasons,  not  the  least  of  which  is  that  in  many  houses 
where  the  operator  has  been  required  to  do  the  rewinding, 
he  will  be  given  just  that  much  additional  time  to  attend 
to  his  projection,  and  thus  the  show  will  be  benefited.  The 


Plate  4,  Figure  141. 


most  important  reason  for  recommending  these  machines, 
however,  is  that  their  general  use  will  very  largely  decrease 
the  damage  done  to  film. 


322 


MOTION    PICTURE    HANDBOOK 


Resistance  as   Applied   to  the 
Projection  Circuit 

RESISTANCE    as    applied    to   the    projection    circuit   is 
no   different   in    principle   from   resistance   applied   to 
any  other  circuit,  but  it  will,  nevertheless,  I  think,  be 
advisable  to  give  somewhat  extended  explanation  of  various 
points,  since  the  element  of  variable  resistance  enters  very 
largely  into  the  matter. 

As  a  rule  the  voltage  of  the  supply  is  a  fixed  quantity, 
which  may  be  anything  from  60  volts  to,  in  extreme  cases, 
500,  but  ordinarily  is  either  60,  70,  110,  or  220. 

The  requisite  amperage  is  an  extremely  variable  quantity, 
ranging  from  as  low  as  .  12  for  stereopticon  projection  to, 
in  extreme  cases,  as  high  as  80,  or  even  90  in  the  projection 
of  moving  pictures.  As  a  general  proposition,  however, 
amperage  requirement  for  moving  picture  projection  will 
range  from  25  to  50  D.  C,  and  from  40  to  60  A.  C,  though 
much  more  than  60  amperes  A.  C.  ought  ordinarially  to  be 
used. 


Figure  142. 


Now  with  a  fixed  voltage,  100  for  example,  the  amperage 
will  depend  upon  the  resistance  encountered.  Having  first 
carefully  read  and  considered  the  text  matter  under  "Re- 
sistance," Page  34,  let  us  examine  the  resistance  of  the  pro- 
jection circuit,  laying  aside,  however,  the  resistance  of  the 
line  and  carbons,  which  is,  in  itself,  a  small  quantity,  usually 
ignored  when  figuring  projection  circuit  resistance. 


FOR    MANAGERS   AND    OPERATORS  323 

If  we  were  to  connect  a  projection  lamp  to  the  supply  lines 
as  indicated  at  A,  Fig.  142,  when  the  carbons  were  brought 
together  a  dead  short  circuit  would  be  established,  which 
would  instantly  blow  a  fuse.  To  avoid  this  we  establish 
resistance  in  the  form  of  a  "rehostat,"  as  at  C,  sketch  B, 
Fig.  142.  This  resistance  operates  precisely  the  same  as 
does  the  resistance  in  the  filament  of  an  incandescent  lamp. 
It  only  allows  a  certain  given  amperage  to  pass,  the  am- 
perage being  dependent  upon  the  voltage  and  the  number  of 
ohms  resistance  contained  in  resistance  C. 

But  right  here  another  equation  enters.  The  foregoing  is 
true  only  so  long  as  the  carbons  remain  in  contact  with  each 
other.  The  instant  they  are  separated  an  arc  is  struck,  and 
additional  resistance  is  established  in  the  arc  itself,  the 
amount  of  which  will  vary  somewhat  with  the  amperage, 
but  more  largely  with  the  distance  the  carbons  are  separated 
from  each  other.  However,  in  picture  projection  it  is  found 
that,  with  a  given  amperage,  there  is  one  certain  distance  at 
which  the  carbons  must  be  separated  from  each  other  in 
order  to  secure  the  best  possible  projection  light,  and  this 
distance  cannot  be  allowed  to  vary  appreciably  without 
injuring  the  illumination  of  the  screen,  nor  does  the  resist- 
ance vary  to  any  large  extent  with  ordinary  differences  in 
amperage.  Therefore  the  resistance  of  the  D.  C.  arc,  when 
it  is  handled  properly,  will  only  vary  between  45  and  55 
volts,  seldom  exceeding  the  latter  quantity  when  operating 
at  its  best,  and  that  of  the  A.  C.  arc  of  ordinary  amperage, 
say  up  to  60,  between  30  and  38. 

In  the  second  edition  of  my  Handbook  I  selected  48  as 
the  figure  fairly  representing  the  voltage  of  the  average 
D.  C.  projection  arc.  I  see  no  reason  to  change  that  figure; 
therefore  we  will  continue  to  consider  the  projection  arc  as 
having  a  voltage  of  48,  with  the  qualification  that  this  is 
subject  to  variation  between  45  and  55.  In  the  same  book 
I  selected  33  as  representing  the  average  voltage  of  the 
A.  C.  arc.  I  think,  however,  in  that  case  35  is  probably 
more  nearly  representative  than  33,  therefore  I  will  now 
change  my  estimate  of  the  average  voltage  of  the  A.  C.  arc 
from  33  to  35,  and  consider  it  as  having  a  voltage  of  35  in 
the  future,  understanding,  however,  as  with  the  D.  C.  arc, 
it  is  a  variable  quantity,  35  being  designed  to  represent  the 
average. 

Now,  having  fixed  all  this  clearly  in  our  minds,  let  us 
proceed  a  little  further.  The  supply  voltage  is,  as  has  been 
said,  fixed,  meaning  that  each  theatre  is  supplied  with  cur- 


324 


MOTION    PICTURE    HANDBOOK 


rent  at  a  certain  given  pressure,  say  110  volts.  One  theatre 
may,  however,  require  35  amperes  D.  C.  and  another  45. 
How  is  each  requirement  to  be  met,  when  both  have  a 
110  volt  supply? 

The  answer  is  simple.  Merely  by  varying  the  amount  of 
resistance  in  rheostat  C,  sketch  B,  Fig.  142.  It  is  also 
possible  that  only  12  or  15  amperes  may  be  required  at  the 
stereopticon  lamp,  which  simply  calls  for  additional  resistance 
in  rheostat  C,  sketch  B,  Fig.  142. 

It  is  not  only  possible,  but  it  is  common  practice  so  to 
arrange  resistance  that  the  amperage  may  instantly  be 
varied  at  the  arc  merely  by  moving  the  lever  of  a  dial 
switch.  This  is  accomplished  by  what  is  known  as  an 
adjustable  rheostat,  the  principle  of  which  is  illustrated  in 
Fig.  143,  in  which  A-B  are  supply  lines,  the  rheostat  in  this 


Figure  143. 

instance  being  connected  into  line  B.  Line  B  connects  to 
lever  6,  which  is  the  arm  or  lever  of  the  dial  switch,  1,  2, 
3,  4  and  5  being  its  contacts.  With  the  lever  on  contact  5, 
as  shown  in  Fig.  143,  it  will  be  readily  seen  that  the  current 
must  pass  through  the  entire  eight  coils  of  the  rheostat, 
therefore  with  the  lever  on  contact  5  the  rheostat  is  supply- 
ing all  the  resistance  it  is  capable  of.  If,  however,  we  move 
the  lever  to  contact  4,  it  will  be  seen  that  the  current  will 
pass  down  the  wire  and  enter  the  resistance  at  the  bottom 
of  coil  a,  thus  eliminating  that  coil,  and,  of  course,  its 
resistance,  which  increases  the  amperage  accordingly.  On 
the  other  hand,  if  lever  6  be  on  contact  3  then  the  resis- 
tance of  two  coils  will  be  eliminated;  if  it  be  on  contact  2, 
three  coils  will  be  eliminated,  and  if  on  contact  1,  four  coils 
will  be  put  out  of  business,  and  we  will  then  only  have  the 


FOR   MANAGERS   AND    OPERATORS  325 

resistance  of  coils  e,  f,  g,  and  h,  which  forms  what  is  known 
as  the  "fixed  resistance"  of  an  adjustable  rheostat. 

The  fixed  resistance  of  the  adjustable  rheostat  must  always 
be  sufficient  to  prevent  enough  current  passing  to  overload 
the  wires  or  grids  composing  the  fixed  resistance. 

This,  I  think,  ought  to  make  the  action  of  the  adjustable 
rheostat  fairly  clear.  The  same  thing  is  seen  photograph- 
ically illustrated  on  Page  338,  Figs.  151  and  152. 

Other  rheostats  called  "fixed  resistance"  rheostats  have  no 
dial  switch.  Their  resistance  cannot  be  varied  without 
removing  the  casing  and  making  a  special  connection.  Still 
other  rheostats  are  built  of  cells,  each  cell  being  a  complete 
rheostat,  containing  a  fixed  amount  of  resistance.  Each'  one 
of  these  cells  may  be  combined  with  the  other  cells,  either 
in  series  or  multiple,  as  will  be. hereinafter  explaind,  so  that 
the  operator  may  vary  the  amperage  by  changing  the  con- 
nections. 

In  considering  Fig.  143,  if  all  the  variable  resistance  is 
"cut  out,"  leaving  only  the  fixed  resistance  to  oppose  the 
voltage,  and  the  coils  or  grids  in  the  fixed  resistance  become 
red  hot,  then  either  the  rheostat  is  not  well  designed,  or 
else  it  is  being  used  on  current  of  higher  voltage  than  it  was 
intended  for.  A  rheostat  will  do  the  work  even  though  its 
coils  or  grids  get  red  hot,  but  if  worked  under  these  con- 
ditions the  life  of  its  coils  or  grids  will  be  very  greatly 
shortened,  and  the  heat  may  at  any  time  become  such  that 
the  metal  will  be  burned  in  two  (fused),  thus  stopping  all 
current  flow. 

It  is  a  very  good  plan  to  have  a  few  extra  rheostat  coils, 
or  grids  on  hand,  so  that  repairs  may  be  made  by  the 
operator  in  case  a  coil  or  grid  burn  in  two.  Making  such 
repairs  ,is  a  comparatively  simple  operation,  requiring  only 
a  fund  of  good  judgment  and  horse  sense,  remembering 
always  that  it  is  absolutely  essential  that  all  coils  or  grids  be 
thoroughly  insulated  from  the  frame  and  casing. 

Remember  that,-  no  matter  what  the  form  of  your  rheostat 
may  be,  whether  round,  rectangular  or  square,  whether  of 
fixed  or  variable  resistance,  Whether  of  coils  or  iron  grids, 
its  electrical  action  is  .always  exactly  the  same.  The 
current  enters  at  one  end  of  a  series  of  coils  or  grids,  passes 
through  each  coil  or  grid  and  loses  a  portion  of  its  voltage 
in  the  process  of  overcoming  the  resistance. 

One  point  puzzles  many  very  good  operators,  viz.:  the 
voltage  of  the  arc  varies  comparatively  but  little,  and  if  it 


326  MOTION    PICTURE   HANDBOOK 

be  true  that  the  voltage  is  reduced  according  to  the  amount 
of  resistance  in  the  rheostat,  why  is  not  the  arc  voltage 
varied  more  greatly  when  a  portion  of  that  resistance  is  cut 
in  or  cut  out  of  the  rheostat? 

This  is  by  reason  of  the  fact  that  the  increased  or  de- 
creased flow  of  current  through  eliminating  a  portion  of  the 
resistance,  or  adding  resistance,  automatically  takes  care  of 
the  matter,  though  it  is  true,  as  has  been  said,  there  is 
some  fluctuation  in  the  arc  voltage  when  the  amperage  is 
changed.  The  whole  question  of  resistance  as  applied  to 
the  projection  arc  is  complicated.  Results  depend  upon  so 
many  different  things  that  it  is  quite  difficult  to  arrive  at  a 
complete  and  clear  understanding  of  the  thing  as  a  whole. 
We  know  how  it  works  and  what  will  be  the  result  of  the 
various  things  we  may  do,  but  it  is  sometimes  rather  diffi- 
cult to  enter  into  detailed  explanation  of  the  exact  why  and 
wherefore  of  these  results. 

Always  thoroughly  insulate  your  .rheostats,  either  by  plac- 
ing on  asbestos,  slate,,  marble,  or  some  other  heat-resisting 
insulating  material.  It  is  always  possible  that  one  of  the 
coils  of  a  wire  coil  rheostat  will  sag  and  touch  the  casing. 
If  the  rheostat  itself  be  thoroughly  insulated  from  the 
ground  no  immediate  harm  will  be  done,  always  provided 
no  other  coil  does  the  same  thing,  but  if  this  happens  and 
the  rheostat  be  grounded  there  is  likely  to  be  a  blown  fuse. 

It  is  also  possible  that  a  coil  may  sag  against  the  casing, 
but  not  form  sufficient  contact  to  allow  of  anything  more 
than  slow  current  leakage.  This  may  not  cause  the  fuses 
to  blow,  but  will  nevertheless  cause  constant  loss  of  power, 
and  that  loss  will  be  registered  on  the  meter.  I  have  known 
of  instances  where  managers  have  complained  of  excessive 
current  bills,  only  to  finally  discover  it  was  due  wholly  and 
entirely  to  this  kind  of  leakage,  Not  enough  current  flowed 
to  cause  excessive  heating,  or  to  affect  the  fuses,  therefore 
the  operator  had  no  suspicion  of  the  existence  of  the  fault. 

Never  place  rheostats  on  an  iron  covered  shelf,  or  on  other 
current-carrying  material  likely  to  produce  a  ground  should 
the  casing  or  frame  of  the  rheostat  become  charged  with  cur- 
rent. Always  place  them  on  insulating  material. 

Temporary  Rheostat  Repairs. — If  a  coil  of  the  rheostat 
should  burn  out  and  you  have  no  other  coil  at  hand,  tem- 
porary repairs  may  be  made  as  per  Fig.  137,  in  which  the 
dotted  line  represents  the  defective  coil,  and  the  black  line 


FOR  MANAGERS  AND  OPERATORS 


327 


a  No.  6  copper  wire,  doubled,  which  has  the  effect  of  elimina- 
ting one  coil.  This  kind  of  repair  will  work  all  right  until 
a  new  coil  can  be  procured  and  installed.  You  may  also 
procure  soft  iron,  from  any  hardware  store,  size  No  8 
(diameter  .128  of  an  inch),  and  make  a  temporary  coil  which 
may  be  installed  in  place  of  the  defective  one;  such  a  coil 
will  work  all  right  for  a  time.  The  wire  may  be  wound 
into  a  coil  by  using  a  mandrill  of  proper  size  set  in  a  lathe, 
or  you  may  wind  it  by  using  a  piece  of  ^  or  J^  inch  gas 
pipe,  or  even  a  broom  handle.  Attach  one  end  of  the  wire  to 
the  pipe,  or  whatever  you  use  for  a  mandrill,  and  the  other 
to  some  fixed  object,  backing  away  the  length  of  the  wire 
and  rolling  the  mandrill  while  you  pull  on -it,  thus  rolling  the 
wire  on  the  mandrill  in  a  close  spiral,  which  must  be  stretched 


Figure  144. 


slightly  endwise  when  installing,  so  that  the  spirals  will  not 
touch  one  another.  There  must  be  not  less  than  1/16  and 
preferably  1/8  inch  between  each  spiral  when  the  coil  is 
installed.  In  installing  a  coil  be  very  certain  it  is  thoroughly 
and  completely  insulated  from  the  frame  of  the  rheostat.' 

Locating  the  Rheostat. — Under  no  circumstances  should 
a  rheostat  be  placed  within  less  than  one  foot  of  any  wall 
containing  inflammable  material,  unless  there  be  a  sheet  of 
H  inch  asbestos  between  it  and  the  wall,  with  at  least  a  1 
inch  air  space  between  the  asbestos  and  wall. 

Rheostats  in  any  case  get  very  warm,  and  when  working  to 
capacity  reach  as  high  as  500  to  600  degrees  Centigrade;  when 


328  MOTION    PICTURE    HANDBOOK 

overloaded  the  coils  or  grids  may  even  become  red  hot,  therefore 
they  MUST  be  thoroughly  protected,  not  only  from  direct  contact 
with,  but  from  close  proximity  to  anything  inflammable. 

It  is  exceedingly  difficult  to  give  advice  as  to  the  best 
location  for  rheostats.  Much  depends  on  local  conditions, 
and  whether  or  not  the  operator  wishes  to  vary  his  amperage 
while  running  the  pictures.  If  he  does  not  wish  to  do  this 

I  would  strongly  advise  that  the  rheostats  be  located  out- 
side  the   operating  room,   this    by   reason    of   the   fact   that 
they  are   in   effect   an   electrical   stove,  and   in   summer   the 
operating  room   is   plenty   hot   enough   without   unnecessary 
heating  apparatus.     Then,  too,  when  located  in  the  operating 
room  there  is  always  the  danger  of  film  coming  into  acci- 
dental   contact   with   them,   with   resultant   call   for   the   fire 
department. 

If  in  the  operating  room  they  should  be  located  on  a  shelf 
near  the  ceiling,  and  as  close  as  possible  to  the  vent  flue. 
If  they  cannot  be  located  near  the  vent  flue,  then  over  them 
should  be  a  metal  hood  connecting  with  a  metal  pipe 
(ordinary  stove  pipe  with  riveted  joints  will  do)  which  should 
extend  through  to  the  open  air,  or,  better  still,  connect  with 
a  chimney  flue,  the  idea  being  to  cause  the  large  amount  of 
heat  generated  by  the  rheostat  to  be  carried  off  into  the 
open  air. 

If  the  operator  has  adjustable  rheostats  and  desires  to  vary 
his  amperage  frequently  it  is  quite  possible  to  locate  them 
at  any  desired  point  inside  the  operating  room  and  by  the 
use  of  levers  control  the  dial  switch  from  operating  position 
at  the  projector. 

Fan  Blowing  on  Rheostat. — In  one  instance,  at  least,  I 
know  of  an  operator  locating  his  45  ampere  rheostat  in 
front  of  a  window,  with  a  12  inch  fan  something  like  2  feet 
from  its  side,  the  rheostat  casing  being  removed.  This 
rheostat  supplied  45  amperes  constantly  to  two  projectors 

II  hours  a  day.     You  could  lay  your  hands  on  the  grids  at 
any  time.     It  looked  like  a  very  good  scheme. 

Examining  Wire  Connections. — It  is  absolutely  essential 
that  the  wire  connections  to  the  rheostat  be  frequently  and 
carefully  examined.  Copper  oxidizes  under  the  action  of 
heat,  and  if  left  too  long  a  thin  scale  of  oxidized  metal  is 
likely  to  form  on  the  wire,  the  lug,  or  both.  This  scale  will 
be  very  thin,  and  practically  invisible,  but  nevertheless  it 
has  very  high  resistance.  My  advice  is  to  take  your  rheostat 
contacts  loose  once  every  week  and  clean  them  thoroughly 


fc  FOR   MANAGERS   AND    OPERATORS  329 

with   emery  cloth,  or  by  scraping,  particularly  if  the  rheo- 
stats  are  working  at   or  near   their   capacity. 

If  your  rheostat  is  delivering  too  much  current  when  all 
the  resistance  is  in,  or  if  it  gets  too  hot,  you  may  reduce  the 
current  to  any  desired  amount  by  mounting  extra  rheostat 
coils  or  coils  made  of  No.  8  soft  iron  wire  on  porcelain  in- 
sulators, as  at  A,  Fig.  144,  Page  327.  Ordinary  porcelain 
or  "knob"  insulators  will  do,  but  behind  the  coils  must  be 
placed  a  thickness  of  54  incn  sheet  asbestos,  or  millboard, 
with  a  1-inch  air  space  between  it  and  the  wall,  and  over 
them  you  should  place  a  wire  screen,  having  about  a  54  mcn 
mesh  to  protect  them  from  accidental  contact  from  film 
or  other  inflammable  substance. 

Iron  Wire  Rheostats. — It  is  quite  possible  to  construct  a 
rheostat  from  ordinary  iron  wire,  but  such  wire  has  a  very 
high  temperature  coefficient,  which  means  that  its  resistance 
increases  rapidly  with  the  increase  of  temperature.  The 
result  of  this  is  that  if  you  build  an  iron-wire  rheostat  to 
give  you  the  amperage  you  want  after  it  has  become  hot,  it 
will  give  altogether  too  much  when  you  first  strike  the  arc. 

Amount  of  Heat  Permissible. — The  heat  in  rheostat  coils 
or  grids  should  in  no  circumstances  exceed  900  degrees 
Fahrenheit.  This  temperature  will  make  rheostat  coils  visible 
in  a  dark  room,  a  dull  red  heat  being  approximately  1300 
Fahrenheit  and  a  cherry  red  1500.  As  a  matter  of  fact  this  is 
too  high  a  temperature  for  true  economy.  Five  hundred  de- 
grees Fahrenheit  is  probaply,  all  things  considered,  as  high 
as  your  rheostat  ought  to  reach  in  temperature.  This  would 
mean  that  the  casing  containing  the  coils  would  probably  not 
reach  a  temperature  in  excess  of  200  degrees  Fahrenheit, 
which  would  eliminate  all  danger  of  fire.  The  life  of  your 
rheostat  will  be  greatly  prolonged  if  it  does  not  exceed  500 
degrees  Fahrenheit,  and  will  be  correspondingly  shortened 
if  it  does  exceed  that  temperature.  You  may  reduce  the 
temperature  of  your  rheostats  by  increasing  their  resistance 
(thus  reducing  the  amperage)  as  per  Fig.  144,  adding  another 
rheostat  in  multiple  to  bring  the  amperage  up  to  what  it  was. 
As  a  matter  of  fact  if  managers  would  install  two  rheostats 
working  at  half  capacity,  instead  of  one  at  full  capacity,  the 
general  results  would  be  better  and  the<  rheostats  last  almost 
forever. 

Two  forms  of  resistance  are  employed  in  rheostats,  viz., 
wire  coils  and  cast-iron  grids.  The  cast-iron  grid  is,  how- 
ever, in  effect,  nothing  more  or  less  than  a  wire  made  of 


330 


MOTION    PICTURE    HANDBOOK 


cast  iron,  and  everything  said  of  one  applies  to  the  other. 
A  grid  rheostat  has  certain  advantages,  also  certain  disad- 
vantages, as  set  below. 


Disadvantages. 

(a)  More       difficult       to       replace 

broken  grids  than  colls. 
Ob)  Heavier  than  coll  rheostat. 
Oc)  Grids  can  be  broken  by  heavy 

Jar. 
Od)  Temperature     co-efficient    less 

fixed,     therefore,     somewhat 

less   reliable. 


Advantages. 

(a)  Better  able  to  withstand  over- 

load and  high  temperatures 
without  damage. 

(b)  Grids    less   likely   to    sag   and 

become      grounded     to      the 
casing  than  colls. 

(c)  Grids  give  longer  service  than 

coils    and    deteriorate    very 
slowly. 

Series  and  Multiple  Connections. — Many  of  the  younger 
operators  are  vastly  puzzled  by  that  really  simple  proposi- 
tion, "series,"  and  "multiple"  connection  as  applied  to 
rheostats. 


Figure  145. 

The  series  connection  is  very  clearly  illustrated  in  Fig. 
145,  in  which  the  voltage  is  opposed  by  the  resistance  con- 
tained in  the  two  two-ohm  rheostats,  plus  the  resistance 
of  the  arc  itself,  the  whole  acting  as  one  unit,  making  a  total 
of  four  ohms  plus  the  resistance  of  the  arc,  which  latter 
wo.uld  be  its  voltage  divided  by  the  number  of  amperes 
flowing.  This  constitutes  a  "series"  connection.  The  term 
series,  as  applied  in  this  connection,  meaning  one  after  the 
other,  or,  in  practice,  the  connecting  of  two  rheostats  in 
such  manner  that  their  total  resistance  will  be  opposed, 
as  one  unit,  to  the  voltage. 

At  B,  Fig.  142,  we  see  another  example  of  series  con- 
nection, in  that  resistance  (rheostat)  C  is  placed  in  series 
with  the  resistance  of  the  arc,  so  that  the  resistance  of  both 
act  as  a  unit.  When  we  connect  a  rheostat  into  a  projection 
circuit  we  term  it  placing  resistance  "in  series  with  the 
arc,"  meaning  that  the  voltage  will  meet  'the  opposition  of 
the  combined  resistance  of  both  the  rheostat  and  the  arc. 

The  multiple  connection  is  equally  simple,  though  to  the 
novice  extremely  puzzling. 


FOR   MANAGERS   AND    OPERATORS 


331 


In  Fig.  146  we  see  a  water  main,  A,  carrying  water,  say 
at  110  pounds  pressure.  Below  is  pipe  B,  which  supplies  a 
large  water  motor,  the  same  being  connected  to  A  by  pipes. 


Figure  146. 

controlled  by  stop-cocks  C  and  D.  Now  it  will  readily  be 
seen  that  with  valve  C  opened  and  valve  D  closed  only  the 
capacity  of  the  pipe  'controlled  by  valve  C  will  reach  pipe 
B  and  the  motor,  whereas,  if  both  valves  C  and  D  are  open 
the  capacity  of  both  pipes  will  enter  pipe  B. 


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Figure  147. 

Now,  turning  to  Fig.  147,  exactly  the  same  proposition 
applies  electrically;  at  B  the  upper  wire,  connecting  to 
binding  posts  1  and  3,  represents  water  pipe  A,  Fig.  146,  the 


332  MOTION    PICTURE    HANDBOOK 

lower  wire,  connecting  to  binding  posts  2  and  4,  and  the  arc 
lamp  represents  pipe  B,  the  arc  itself  represents  the  water 
motor,  and  the  resistance  in  each  rheostat  represents  a  pipe 
and  valve  corresponding  to  C  and  D,  Fig.  146.  The  action 
of  the  water  in  Fig.  146  and  the  action  of  current  in  Fig. 
147  would  be  identical.  Each  rheostat  is  a  25  ampere,  110 
volt  instrument,  meaning  that  it  has  just  enough  resistance 
to  .allow  25  amperes  to  flow  when  connected  in  series  with  a 
48  volt  arc,  and  opposed  to  110  volts  pressure.  Under  the 
conditions  shown  in  Fig.  147,  25  amperes  will  flow  from  the 
upper  wire  through  binding  post  1  and  the  resistance  of  the 
rheostat  to  binding  post  2,  and  thence  to  the  arc;  25  amperes 
will  also  flow  from  binding  post  3  through  the  resistance  of 
the  second  rheostat  to  binding  post  4,  and  thence  to  the  arc, 
joining  the  25  amperes  coming  from  the  first  rheostat,  and 
thus  50  amperes  will  be  delivered  at  the  arc. 

The  idea  is  perhaps  a  little  more  clearly  shown  at  A, 
Fig.  147,  in  which  the  dotted  line  is  used  to  represent  the 
passage  of  the  current  through  the  resistance  of  the  rheostat 
from  binding  post  1  and  2  and  3  and  4.  A  and  B,  Fig.  147, 
are  identical,  except  that  B  is  a,  diagrammatic  top  view, 
whereas  A  is  a  side  view  showing  the  wires  about  as  they 
would  appear  in  practice.  The  multiple  connection  is  shown 
photographically  in  Fig.  148,  Page  335. 

Any  number  of  rheostats  of  different  voltage  may  be  con- 
nected in  series,  provided  the  total  resistance  of  the  whole  be 
sufficient  to  reduce  the  current  flow  to  a  point  where  the 
resistance  will  not  be  overloaded. 

Any  number  of  rheostats,  each  having  sufficient  resis- 
tance to  oppose  the  line  voltage  without  overload,  may  be 
connected  in  multiple,  regardless  of  their  amperage  capacity. 
For  instance,  a  25  ampere,  a  12  ampere  and  a  50  ampere  110 
volt  rheostat  could  be  connected  in  multiple  on  110  volts, 
and  the  result  would  be  current  delivery  equal  to  their 
combined  capacity,  or  87  amperes. 

You  can  use  a  220  volt  rheostat  on  110  volts,  or,  for  that 
matter,  on  60  volts,  but  you  would  only  get  amperes  equal 
to  220  minus  the  arc  voltage  divided  by  the  resistance  of 
the  rheostat.  The  resistance  of  such  a  rheostat  would  be 
(220  —  48)  -^by  its  rated  amperage  on  220  volts.  You  cannot, 
however,  connect  110  volt  rheostats,  either  singly  or  in 
multiple,  on  220  volts,  since  there  is  not  resistance  sufficient 
to  withstand  that  pressure.  The  coils  would  quickly  become 
overheated  and  would  soon  burn  out.  You  may,  however, 


FOR    MANAGERS    AND    OPERATORS  333 

connect  two  110  volt  rheostats  in  series  on  220  volt  current 
(though  they  would  be  slightly  overloaded),  by  reason  of 
the  fact  that  you  would  be,  in  effect,  making  one  rheostat  out 
of  the  two,  and  would  thus  present  double  the  resistance 
required  for  110  volts. 

You  may  use  a  rheostat  built  for  certain  voltage  on  that 
pressure,  or  anything  less  than  that  pressure,  but  you  cannot 
use  a  rheostat  on  a  higher  pressure  than  it  was  intended  for, 
except  it  be  placed  in  series  with  additional  resistance. 

This,  however,  may  be  qualified  to  the  extent  that  a 
rheostat  built  for  a  certain  voltage  may  usually  be  used 
on  current  five,  ten,  or  even  fifteen  volts  in  excess  of  that 
pressure. 

A.  C.  and  D.  C.  Rheostats. — There  is  no  such  thing  as 
a  "D.  C."  or  an  "A.  C."  rheostat.  Any  rheostat  will  work  on 
either  A.  C.  or  D.  C.,  but  a  rheostat  that  will  deliver  30  amperes 
when  working  with  a  D.  C.  projection  arc,  on,  say,  110  volts 
pressure,  will  deliver  considerably  more  on  the  same  voltage 
A.  C.,  by  reason  of  the  fact  that  the  A.  C.  projection  arc  is 
shorter,  hence  offers  less  resistance,  so  that  the  total  resis- 
tance opposed  to  the  current  is  reduced. 

This,  however,  is  again  qualified  by  the  fact  that  there  is  a 
tendency  to  induction  when  a  wire-coil  rheostat  is  used  on 
A.  C.,  which  has  the  effect  of  adding  inductive  resistance, 
or,  in  other  words,  magnetic  kick.  The  amount  of  inductive 
resistance  thus  set  up  will  vary  with  the  size  of  the  coils, 
their  length  and  the  closeness  of  the  spirals.  It  amounts  to 
something,  but  not  very  much.  The  inductive  effect,  however, 
causes  vibration  in  the  coils,  and  as  a  result  some  wire-coil 
rheostats  are  very  noisy  when  used  on  A.  C.  This  noise  may 
be  reduced  by  packing  the  center  of  the  wire  coils  tightly 
with  shredded  asbestos  forced  in  at  the  end  of  each  coil. 

The  use  of  rheostats  on  A.  C.  is  very,  very  bad  practice.  It 
is  unnecessarily  wasteful.  Where  alternating  current  is  used 
rheostats  should  be  replaced  by  low  voltage  transformers.  See 
Page  343,  or,  better  still,  with  a  mercury  arc  rectifier  or  motor 
generator  set,  see  index. 

If,  however,  for  any  reason  it  is  necessary  to  use  resistance 
in  A.  C.  projection  circuits  I  would  advise  the  grid  type, 
since  they  are  likely  to  be  a  great  deal  less  noisy;  also  there 
is  much  less  inductive  effect;  therefore  the  resistance  will 
be  found  to  be  more  stable. 

Rheostats  Extremely  Wasteful.— The  real  use  of  the 
rheostat  in  the  projection  circuit  is  to  consume  the  differ- 


334  MOTION    PICTURE    HANDBOOK 

ence  between  the  line  voltage  and  the  arc  voltage,  or,  in 
other  words,  to  break  the  line  voltage  down  to  the  value 
of  the  arc  voltage.  This  represents  an  absolute  waste  of 
energy,  since  the  difference  between  the  line  voltage  and 
the  arc  voltage  is,  and  must  be,  dissipated  in  the  form  of 
utterly  useless  heat  generated  by  the  rheostat,  and  this  wast- 
ed energy  is  all  registered  on  the  meter  and  must  be  paid  for 
by  the  theatre. 

Suppose,  for  example,  the  current  supply  be  110  volts, 
and  that  we  use  40  amperes  at  the  arc.  Voltage  times 
amperes  equals  watts,  therefore  110X40  =  4400  watts  reg- 
istered by  the  meter.  The  average  voltage  of  a  D.  C.  pro- 
jection arc  is  only  48,  therefore  there  must  be  consumed  in 
the  rheostat  110  —  48  =  62  volts,  which  will  be  registered 
on  the  meter  as  62  X  40  =  2480  watts,  this  amount  being 
absolute  waste.  We  are  using  a  total  of  4400  watts,  and 
only  actually  employing  4400  —  2480  =  1920  watts  in  the 
production  of  light.  At  this  voltage  and  amperage  the  rheo- 
stat is  43J4  per  cent,  efficient. 

This  is  bad  enough,  but  if  the  voltage  be  higher,  say  220, 
then  ,the  proportion  of  waste  becomes  literally  enormous. 
Using  40  amperes  from  220  volt  lines  through  a  rheostat 
would  mean  220  X  40  =  8800  watts  registered  by  the  meter, 
whereas  the  actual  wattage  at  the  arc  is,  as  in  the  former  case, 
48  X  40  =  1920  watts,  so  there  is  wasted  in  the  resistance  of 
the  rheostat  8800  —  1920  =  6880  watts,  or  about  3l/2  times 
as  much  energy  as  is  actually  employed  in  the  production  of 
light.  On  the  other  hand,  if  the  voltage  were  only  60  or  70 
then  the  waste  in  resistance  would  be  correspondingly  less, 
and  it  is  for  this  reason  why  the  author  has  always  advised 
theatre  managers  when  purchasing  a  light  plant  for  their 
theatre  to  get  a  60  or  70  volt  generator. 

From  what  has  been  said  the  idea  may  be  gained  that  if 
direct  current  were  generated  at  from  45  to  55  volts,  or 
alternating  current  at  30  to  35  volts,  it  would  be  possible 
to  operate  without  any  resistance  at  all,  thus  eliminating  all 
waste.  This,  however,  is  only  true  where  generators  of  a 
certain  type,  built  especially  for  this  kind  of  work,  are  used. 
By  the  use  of  certain  types  of  generators  which  in  themselves 
automatically  regulate  the  voltage,  hence  the  current  flow, 
it  is  possible  to  operate  a  projection  arc  without  any  resis- 
tance at  all  (See  Motor  Generator  Sets,  further  on),  but 
this  cannot  be  done  when  using  the  usual  type  of  generator. 
Resistance  performs  two  functions,  vfiz.,  regulates  the  am- 


FOR   MANAGERS   AND   OPERATORS 


335 


perage  by  regulating  the  voltage  and  supplies  a  steadying 
influence,  or  sort  of  "cushion"  for  the  arc.  Without  this 
steadying  influence,  or  its  equivalent  in  another  form,  such 
as  a  generator  of  the  type  mentioned,  the  arc  would  be  so 
unstable  that  it  could  not  be  handled  at  all;  also  it  would 
not.  be  practical  to  strike  the  arc  in  the  first  place,  because 
when  the  carbons  were  brought  together  it  would  establish 
a  dead,  short  circuit  which  would  instantly  blow  the  fuses. 
Note. — I  have  said  that  all  pressure  above  arc  voltage 
represents  waste,  but  this  is  not  strictly  true  as  applied  to 
projection  arcs  taking  current  through  rheostats.  Under 
these  conditions  if  the  suply  be  below  60  volts  the  necessary 
resistance  is  not  sufficient  to  steady  the  arc,  therefore,  strict- 
ly speaking,  while  the  voltage  between  a  60  volt  supply 
pressure  and  arc  voltage  represents  waste,  still  it  is  necessary 
waste,  whereas  when  the  supply  voltage  is  more  than  60  all 
over  that  figure  is  unnecessary  waste. 


A 


Figure  148. 

Note  b. — It  may  be  remarked  that  traveling  exhibitors 
have  installed  a  small  generator  in  an  automobile  and,  using 
the  auto  engine  for  power,  have  operated  a  projection  lamp 
without  resistance  in  circuit.  This  is  possible  with  a  small 
generator  working  right  up  to  capacity,  but  is  not  possible 
when  taking  current  from  power  lines  or  a  generator  of 
considerable  capacity. 

Figuring  Rheostat  Connections.— In  Fig.  148  we  see  an 
Edison  adjustable,  grid  rheostat,  with  part  of  the  casing  re- 
moved to  show  the  grid  bank,  connected  in  multiple  with  a 
Power's  non-adjustable  coil  rheostat,  both  110  volt  instru- 
ments. 


336  MOTION    PICTURE    HANDBOOK 

The  Power's  is  a  25  ampere,  110  volt,  and  the  Edison  a  25 
to  40  ampere,  110  volt  rheostat.  We  will  therefore  get  25 
amperes  through  one,  and  from  25  to  40  through  the  other, 
according  to  how  the  adjustment  switch  is  turned.  We  will 
have  a  total  current  of  from  25  +  25  =  50,  to  25  +  40  =  65  am- 
peres at  the  arc,  with  this  combination.  With  the  same  two 
connected  in  series  on  D.  C.  we  would  get  from  10  to  12+ 
amperes.  It  is  figured  as  follows:  The  Power's  is  a  25  am- 
pere, 110  volt  instrument,  therefore,  has  (110  —  48)  -f-  25  = 
2y2  ohms  resistance.  The  Edison,  when  working  at  25  amperes 
must  have  the  same  resistance,  hence  there  will  be  a  total 
of  2*/2.  +  2y2  ohms  when  they  are  opposed  to  the  voltage  in 
series.  The  resistance  of  the  arc  will  be  approximately  1 
ohm,  hence  (110  —  48)^-2^+2^  +  1  will  equal  the  amper- 
age when  the  Edison  is  on  the  25  ampere  contact.  This  is 
practically  10  amperes.  If  the  Edison  is  set  on  the  40  am- 
pere contact  we  would  then  have  (110  —  48)^-40  equal  prac- 
tically \l/2  ohms,  which  added  to  the  resistance  of  the  Pow- 
er's makes  (2l/2  +  \l/2}  —4  ohms.  We  would,  therefore,  have 
(110  —  48)  -f-  2y2  +  1J*X1  =  12+  amperes  delivery.  If  the 
current  be  A.  C.,  then  we  would  have  (110  —  35) -f- 5  =  15 
amperes  (not  taking  the  inductive  resistance  into  account); 
the  A.  C.  arc  voltage  being  35,  instead  of  48  as  in  D.  C. 

Let  it  be  clearly  understood,  however,  that  these  figures  are 
only  approximate.  It  is  impossible  to  be  accurate  for  the  rea- 
son that  arc  resistance  varies  with  the  length  of  the  arc; 
also  the  rheostatic  resistance  varies  with  (a)  temperature 
of  the  coils  or  grids;  (b)  with  their  age.  Also,  merely 
because  a  rheostat  is  stamped'  "110  volt,  25  ampere,"  it  does 
not  follow  it  has  exactly  the  resistance  this  would  indicate. 
Moreover,  the  supply  voltage  may  not  be  just  what  you 
think  it  is. 

As  a  matter  of  fact,  a  wire-coil  rheostat  rated  at  25  am- 
peres, and  which  delivers  that  amperage  when  new,  will  not 
do  so  after  it  has  been  used  for  a  time.  The  resistance  of 
wire  coils  rises  gradually  for  a  time,  and  then  remains  prac- 
tically stationary  until  the  coils  finally  give  out  entirely. 
When  the  resistance  reaches  its  highest  point  it  will  usually 
be  found  that  the  "25  ampere"  wire  coil  rheostat  is  really 
delivering  about  20  amperes.  After  using  a  wire  coil  rheostat 
for  a  month  or  more  you  will  be  more  nearly  correct  if  you 
subtract  five  amperes  from  every  25  amperes  of  its  rated 
capacity. 


FOR    MANAGERS   AND    OPERATORS  337 

This  may  or  may  not  apply  to  any  considerable  extent  to 
cast  iron  grids.  It  is  claimed  that  the  resistance  of  cast  iron 
remains  constant,  or  practically  so,  but  of  this  I  am  not 
certain. 


Resistance  Devices 

EACH  machine  manufacturer  puts  out  a  rheostat,  and 
some  of  them  put  out  two  or  three  different  kinds. 
The  Nicholas  Power  Company,-  for  instance,  puts  out  a 
grid  rheostat  and  two  or  three  different  varieties  of  wire 
coil  rheostats.  I  do  not  believe  it  is  necessary  to  present 
illustrations  of  all  these  different  devices,  particularly  in  view 
of  the  fact  that  they  all  operate  on  precisely  the  same  prin- 
ciple, and  in  exactly  the  same  way.  Wire  coil  rheostats  are 
nothing  more  or  less  than  a  long  piece  of  resistance  wire 
coiled  up  into  spirals  in  order  to  save  space,  the  coils  being 
mounted  on  an  iron  frame,  from  which  they  are  thoroughly 
insulated,  the  whole  being  protected  by  a  sheet  metal  guard 
or  cover.  The  current  enters  at  one  binding  post,  flows 
through  the  resistance,  and  leaves  at  the  other  binding  'post. 
The  rheostat  is  connected  into  either  wire  of  the  circuit, 
though  most  operators  prefer  the  positive  wire. 


Figure  149. 

Fig.  149  shows  an  ordinary  rheostat  "coil."  In  mounting 
this  coil  must  be  stretched  just  a  little— enough  so  that  the 
spirals  will  be  at  least  1/16  of  an  inch  apart.  This  is  im- 
portant, by  reason  of  the  fact  that  if  the  spirals  touch  each 
other,  then  the  current  will  simply  jump  through  the  coil, 
instead  of  flowing  through  the  entire  length  of  the  wire. 
The  effect  of  the  spirals  touching  would  tend  to  eliminate 
a  large  percentage  of  the  resistance. 

Fig.  150  illustrates  one  grid  of  a  rheostat.  It  will  be  ob- 
served that  it  is,  in  effect,  precisely  the  same  as  the  wire 
coil  illustrated  in  Fig.  149.  To  all  intents  and  purposes  it 
is  a  long  wire  made  of  cast  iron  coiled  up  to  save  space. 


338 


MOTION    PICTURE    HANDBOOK 


In   Fig.   151  we   see  a  photographic   representation  of   an 
adjustable  grid  rheostat.    Thirteen  to  26,  inclusive,  are  cast 


Figure  150. 

iron  grids,  the  same  as  the  one  illustrated  in  Fig.  143.    The 
edges  of  these  grids  are  protected  from  breakage  by  metal 


Figure  151. 

guards,   1    and   3,    Fig.    151,    inside   of   which    is    a   layer   of 
asbestos    insulation.      At    the    top,    X    is    a    metal    spacing 


FOR    MANAGERS   AND    OPERATORS  339 

washer;  next  to  it,  0  represents  a  similar  spacing  washer,  but 
between  it  and  the  grids  are  insulating  washers.  Next  comes 
another  current  carrying  washer,  and  then  another  insulat- 
ing washer,  the  whole  being  mounted  on  tie-rods  4-4.  Now 
between  grids  25  and  26  at  the  bottom  end  is  an  insulated 
spacing  washer,  and  next  to  it,  F  is  a  current  carrying 
washer,  and  so  on.  The  grids  are  insulated  from  the  tie- 
rods,  therefore  you  will  readily  see  that  current  entering 
at  binding  post  9  will  pass  through  the  connections  to  binding 
post  G,  thence  to  grid  26,  up  its  length,  across  current  carry- 
ing washer  X,  down  grid  25,  across  current  carrying  washer 
F,  up  grid  24,  and  so  on  until  it  reaches  an  outlet.  At  the 
other  end,  11  is  a  binding  post  to  which  the  wire  is  attached, 
this  post  connecting  to  central  switch  post  6  through  a 
wire,  12,  represented  by  dotted  line;  1,  2,  3,  4  and  5  are  con- 
tact buttons  connected  to  the  grids  at  points  A,  B,  C,  D 
and  E. 

The  lever  is  now  on  contact  5,  so  that  current  entering 
at  binding  post  9  will  flow  to  binding  post  G  and  through 
the  grids  until  it  reaches  binding  post  E,  whence  it  will  flow 
up  through  the  wire  jumper  to  switch  contact  5,  across  the 
switch  lever  to  post  6,  down  wire  12  to  binding  post  11,  and 
thence  to  the  lamp.  This,  you  will  readily  see,  "  cuts  out " 
grids  13,  14,  15,  16,  17,  18,  19  and  20.  If  we  swing  switch 
lever  7  over  to  contact  button  1  the  current  must  then  travel 
through  the  grids  until  it  reaches  binding  post  A,  whence 
it  will  flow  to  contact  1  and  around  through  the  switch  lever 
and  wire  12  to  binding  post  11,  thence  to  the  lamp.  There- 
fore, with  switch  lever  7  on  contact  1  you  will  be  getting  all 
the  resistance  that  particular  rheostat  is  capable  of  supply- 
ing, and  will  be  reducing  the  voltage,  and  therefore  the  am- 
perage as  much  as  that  rheostat  will  reduce  it. 

Binding  post  8  is  an  auxiliary  binding  post  not  found  on 
most  rheostats.  It  is  for  the  purpose  of  allowing  the  rheo- 
stat to  be  used  on  low  voltage  current. 

With  switch  lever  7  on  contact  5,  and  the  wire  connected 
to  binding  posts  11  and  9,  you  still  have  the  resistance  sup- 
plied by  grids  21,  22,  23,  24,  25  and  26.  This  is  what  is 
known  as  the  "fixed  resistance"  of  the  rheostat.  If  you 
desire  to  use  the  rheostat  on  current  of  very  low  voltage 
this  resistance  might  be  too  much  to  supply  the  required 
amperage,  and  by  changing  the  connection  from  binding 
post  9  to  binding  post  8  you  will  cut  out  coils  25  and  26, 
thus  lowering  the  fixed  resistance  by  one-third,  and  increas- 
ing the  amperage  accordingly. 


340 


MOTION    PICTURE    HANDBOOK 


This  is  made  somewhat  more  plain  in  Fig.  152,  in  which 
the  same  numbers  are  used.  By  closely  examining  Fig.  152, 
you  will  observe  the  mica  insulating  washers,  which  are 
shown  at  10  in  both  figures,  you  will  see  they  are  only  used 
in  alternate  spaces.  The  Power  Company  puts  this  type  of 
rheostat  out  for  both  110  and  220  volt  current.  The  weight 
of  the  220  volt  rheostat  is  practically  double  that  of  the 
110  volt  instrument. 


Figure  152. 

In  connecting  a  rheostat,  wires  are  run  from  the  main 
operating  room  cutout  to  one  side  of  the  machine  table 
switch,  and  one  of  the  contacts  at  the  other  end  of  the 
machine  table  switch  is  connected,  using  asbestos  covered 
stranded  wire,  direct  to  one  of  the  binding  posts  of  the 
lamp.  From  the  other  machine  switch  binding  post  we  run 
an  asbestos  strand  covered  wire  to  one  (either)  of  the 
rheostat  binding  posts,  and  from  the  other  rheostat  binding 
post  we  run  another  asbestos  covered  strand  wire  to  the 
other  binding  post  of  the  lamp.  Most  operators  prefer  the 
resistance  in  the  positive  wire  when  using  D.  C.,  but  it 
really  does  not  make  any  particular  difference  which  wine 
it  is  in. 

The  rheostat  shown  in  Fig.  151  may  be  disassembled  by 
removing  its  cover,  and  loosening  nuts  4-4  which  hold  the 
grid  bank  together.  Having  removed  these  nuts  the  grids 
can  be  slipped  off  the  tie-rods.  In  reassembling  be  very  sure 


FOR   MANAGERS   AND    OPERATORS  341 

you  get  the  insulating  and  current  carrying  washers  X  and  O  in 
their  proper  relation.  If  you  don't  you  will  have  trouble.  Also 
when  the  reassembling  is  complete  be  sure  to  set  up  tie-rods  4-4 
good  and  tight. 

Caution. — Be  sure  that  lever  7  makes  firm  contact  with 
the  contact  buttons,  since  otherwise  there  will  be  arcing  and 
heating.  Should  these  contacts  become  roughened  after  a 
time,  carefully  dress  them  up  with  No.  00  emery  cloth  or 
paper,  at  the  same  time  smoothing  up  the  contact  face  of 
the  lever.  Wrapping  the  emery  around  a  small  file  will 
enable  you  to  do  a  better  job.  All  adjustable  rheostats  have 
the  same  connections  as  the  one  shown  in  Fig.  151,  except 
that  few  have  auxiliary  binding  post  8.  The  220  volt  grid 
rheostat  is  connected  into  the  circuit  just  the  same  as  is  the 
110  volt  one. 

Some  rheostats  are  adjustable,  and  some  are  non-adjust- 
able, the  latter  usually  having  two  binding  posts  to  which 
wires  are  connected.  They  offer  fixed  resistance  which  can- 
not be  changed.  This  kind  of  resistance  is  not  the  best, 
however,  for  several  reasons,  one  of  which  lies  in  the  fact 


Figure  153. 


that  a  new  rheostat  has  considerable  less  resistance  than  it 
has  after  it  has  been  in  use  for  a  time.  Therefore,  if  for  no 
other  reason  it  is  desirable  that  one  be  able  to  cut  out  some 
of  the  coils  when  the  resistance  becomes  greater  through  use. 
As  between  the  grid  and  wire  coil  rheostat  I  would  advise 
the  wire  coil  for  road  use,  by  reason  of  its  comparatively 
light  weight,  and  the  grid  rheostat  for  theatrical  use,  be- 
cause it  is  rugged  in  its  construction,  deteriorates  much  less 
rapidly  and,  therefore,  lasts  longer.  For  road  use  the 
Nicholas  Power  Company  puts  out  a  wire  coil  rheostat 
made  in  round  form,  illustrated  in  Fig.  153. 


342 


MOTION    PICTURE    HANDBOOK 


My  reason  for  recommending  this  rheostat  is  it  is  light  in 
weight  and  very  flexible  in  its  electrical  action. 

In  Fig.  154  the  top  of  this  rheostat  is  shown  at  A,  on  the 
left.  Connections  are  made  to  binding  post  B-B,  and  all 
the  coils  from  1  to  14  are  thus  placed  in  series  with  each 
other,  but  since  binding  post  B  connects  to  the  central 
switch  post  by  means  of  a  copper  jumper  the  current  will 
only  pass  through  the  number  of  coils  necessary  to  reach 
the  lever.  Therefore,  if  the  lever  is  on  contact  4  the  re- 
sistance of  coils  1,  2  and  3  would  be  eliminated.  At  B,  on 


Figure  154. 


the  right,  this  rheostat  is  shown  with  its  two  sides  in  mul- 
tiple. It  is  the  same  as  though  you  connected  two  rheostats, 
each  one  having  the  resistance  supplied  by  half  the  total 
number  of  coils  in  the  rheostat,  in  multiple.  The  current 
enters  at  binding  posts  B-B,  flows  through  the  coils  on  the 
left  to  8  and  through  the  coils  on  the  right  to  7,  and  thence 
to  the  lamp.  You  thus  get  the  full  capacity  of  these  two 
banks  of  coils,  but  this  can  only  be  used  on  110  or  less  voltage, 
whereas  the  connection  at  A  can  be  used  on  current  up  to 
240  volts.  When  using  connection  B,  Fig.  154,  the  lever  must 
be  set  on  contact  1.  Possibly  you  can  increase  the  current 
somewhat  by  moving  it  to  contact  2  or  3,  but  beyond  that 
the  remaining  coils  on  that  side  will  most  likely  get  red  hot. 


FOR   MANAGERS   AND    OPERATORS 


343 


The  Transformer 

THE  transformer  .is   a  device   for  changing   alternating 
current  of  a  given  cycle   (frequency)   and  voltage  to 
the  alternating  current   of  the   same   cycle   but  of  a 
different  voltage  and  amperage.     In  general,  the  volts  times 
amperes  taken  from   the   supply   line  is   equal   to  the  volts 
times   amperes    (volt  amperes)    given  off  at  the   secondary, 
less  the  loss  in  the  transformer  itself,  which  loss  varies  from 
10  to  20  per  cent. 

The  standard  transformer  is  made  up  with  two  separate 
coils  which  are  insulated  from  each  other,  one  coil  being 
called  "primary "  and  the  other  coil  being  called  "  sec- 
ondary." There  are  modifications  of  transformers  which  are 
designed  as  "  auto  transformers,"  in  which  the  transform- 
ing action  is  obtained  more  efficiently  than  with  a  straight 
transformer,  but  in  which  the  windings  are  not  insulated 
from  one  another,  the  secondary  winding  becoming  a  part  of 
the  primai  y  winding.  To 
this  class  belong  most 
transformers  used  in  the 
operating  rooms  for  con- 
trolling the  projection  arc. 
Another  modification  is  a 
reactance  coil,  or  choke  coil, 
as  it  is  sometimes  called. 
In  this  device  the  choking 
effect  of  the  transformer  Figure  155. 

is    obtained,   but   the   am- 
peres taken  from  the  secondary  side  will  always  be  the  same  as 
on  the  primary  side,  although  the  volts  on  the  secondary  side 
will  differ  from  the  volts  on  the  primary  side.     This  device  is 
less  efficient  than  either  the  transformer  or  auto  transformer. 

A  transformer  (or  auto  transformer)  may  either  increase 
the  voltage  and  decrease  the  amperage,  in  which  case  it  is 
called  a  step-up  transformer,  or  it  may  decrease  the  voltage 
and  increase  the  amperage,  in  which  case  it  is  called  a  step- 
down  transformer. 

Fig.  155  represents  the  diagrammatic  connections  of  a 
straight  transformer.  It  will  be  noted  that  the  windings 


344 


MOTION    PICTURE    HANDBOOK 


are   independent   of   one    another,   although    they   both    sur- 
round portions  of  the  same  core  or  magnetic  circuit. 

Fig.  156  represents  the  diagrammatic  arrangement  of  an 
auto  transformer.  It  will  be  noted  that  with  the  two  wind- 
ings connected  together  so  as  to  form  practically  one  coil, 
due  to  the  fact  that  the  current  in  the  primary  is  transformed 
through  only  a  part  of  the  winding,  the  losses  become  less 
tlhan  the  losses  in  the  transformer  represented  in  Fig.  155. 
This  results  in  a  smaller  and  more  efficient  construction 
than  in  the  straight  transformer. 

Fig.  159  is  a  diagrammatic  connection  of  a  reactance  or 
choke  coil.  With  this  arrangement  no  saving  in  wire  size 
is  possible,  because  the  same  amount  of  current  (amperes) 

consumed  in  the  arc  must  be 
taken  from  the  line. 

In  a  transformer  or  auto 
transformer  the  amount  of 
current  in  secondary  depends 
on  the  ratio  of  turns  (number 
of  turns  primary  divided  by 
number  of  turns  secondary). 
If  the  primary  winding  were 
made  up  with  20  turns  and 
the  secondary  winding  made 
up  with  10  turns,  this  would 
be  a  ratio  of  2  to  1,  and  each 
two  amperes  in  the  secondary 
would  require  one  ampere 
from  the  primary.  The  volts 
on  the  secondary,  however, 
would  be  only  one-half  of  the 
volts  on  the  primary. 

Referring  to  Fig.  157,  A  and 
B  are  the  wires  of  the  sup- 
ply circuit;  C  and  D  are  wires  leading  to  the  primary  coil 
from  the  main  supply  wires;  I  and  J  are  wires  leading  from 
the  secondary  coil  to  arc  lamp  K;  L  is  the  laminated  iron 
core. 

The  primary  and  secondary  coils  may  be  wound  one  over 
the  other  and  inserted  in  the  opening  in  the  core,  or  they 
may  be  wound  as  shown,  or  in  other  ways,  the  method  in 
Fig.  155  being  merely  selected  to  show  the  idea.  The  wires 
of  the  coils  are  themselves  covered  with  a  special  form  of 
insulation.  The  coils  are  insulated  from  the  iron  core. 


Figure  156. 


FOR   MANAGERS   AND    OPERATORS 


345 


Neither  coil   has  any  mechanical  or  electrial   connection   of 
any  kind  whatsoever  with  the  other  coils  or  the  core. 

The  core  itself  is  built  up  of  thin  sheets  of  annealed 
steel.  It  is  essential  that  these  sheets  be  very  thin,  the  exact 
thickness  depending  on  the  frequency  of  the  current.  Each 
s(heet  is  painted  on  both  sides  with  an  insulating  compound, 
or  other  methods  to  insulate  are  used,  after  which  the  s'heets 
are  clamped  firmly  together  and  the  primary  and  secondary 
coils  are  wound  on  the  core  thus  formed,  over  a  layer  of 
insulating  material,  and  the  two  coils  and  the  core  form  the 
transformer. 

The  action  is  as  follows:  When  the  switch  on  the  pri- 
mary side  is  closed  the  current  which  flows  through  the 
primary  coil  magnetizes 
the  iron  core  and  sets  up  a 
powerful  magnetic  field, 
Which  has  the  effect  of  mak- 
ing a  choke  coil  out  of  the 
primary  coil,  and  a  choke 
coil  so  powerful  that  prac- 
tically no  current  at  all  will 
flow  when  the  secondary 
circuit  is  open.  The  mag- 
netic field  thus  created  sur- 
rounds both  primary  and 
secondary  coils,  so  that 
w.hile  these  coils  have  ab- 
solutely no  mechanical  con- 
nection with  each  other  or 
with  the  core,  and  are,  in 
fact,  thoroughly  insulated 
from  the  core,  they  do  have 
a  magnetic  connection,  which 
acts  as  follows : 

It  is   one   of   the   laws   of  Figure  157. 

electrdcity  that)  all,  wires  carry- 
ing alternating  current  are  surrounded  with  what  is  known  as  a 
"magnetic  field";  that  is  to  say,  for  a  certain  distance  sur- 
rounding a  wire  carrying  A.  C.  the  air  is  permeated  with 
magnetism.  Now  if  another  wire  be  placed  within  this  mag- 
netic field,  as  per  Fig.  158,  although  there  be  no  mechanical 
connection  of  any  kind  between  the  two  wires,  if  wire  A 
carries  A.  C.  then  there  will  be  an  induced  electro-motive 
force  set  up  in  wire  B,  though  under  the  conditions  set  forth 
the  effect  would  be  too  slight  to  be  perceptible  except  to  a 


346 


MOTION    PICTURE    HANDBOOK 


Figure  158. 


very  delicate  galvanometer.  Fig.  158  merely  illustrates  the 
theory  upon  which  the  transformer  depends  for  its  action. 
In  transformers  instead  of  wire  A  we  have  a  great  many 
wires  in  the  primary  coil  or  rather  one  wire  passing  through 
the  magnetic  field  a  great  many  times,  and  instead  of  wire 

B  a  great  many  wires  in  the 
secondary  coil,  or  one  wire 
passing  through  the  magnetic 
field  a  great  many  times.  We 
also  have  an  iron  core  which 
enormously  intensifies  the  mag- 
netic field,  and  thus  the  feeble 
action  in  wire  B,  Fig.  158,  be- 
comes enormously  powerful,  and' 
we  have  the  "transformer." 

The  action  of  the  transformer 
is  entirely  automatic,  and  it 
depends  entirely  for  its  action 
on  magnetic  inductance.  The 
secondary  current  in  flowing 
through  the  secondary  coil  magnetizes  the  core,  but  in  the 
opposite  direction  to  the  primary,  therefore  when  current 
flows  in  the  secondary  the  primary  current  increases  just 
enough  so  that  combined  effect  of  the  two  windings  remains 

the  same.    It  therefore  fol-      

lows  that  when  the  load  of 
a  transformer  is  increased 
the  primary  winding  auto- 
matically takes  additional 
current  from  the  supply 
wires  just  sufficient  to  sup- 
ply the  added  load  on  the 
secondary,  therefore  the 
automatic  action  of  the 
transformer  depends  on  the 
balanced  magnetizing  action 
of  the  primary  and  second- 
ary circuits. 

Referring  to  Fig.  156,  A 
and  B  are  the  supply  lines, 
C  and  D  are  the  wires 


Figure  159. 


feeding  the  auto  transformer,  E  the  winding,  including  both 
primary  and  secondary,  F  and  G  the  wires  feeding  the  arc  K, 
and  L  is  the  iron  core. 

It  is  to  be  noted  the  entire  coil  E  is  connected  across  the 


FOR   MANAGERS   AND    OPERATORS 


347 


supply  lines  and  that  a  tap  T  is  brought  out  so  that  the 
section  of  E  from  S  to  T  forms  the  secondary  while  the 
whole  coil  forms  the  primary.  The  action  electrically  and 
magnetically  is  the  same  as  in  a  standard  transformer. 

The  choke  coil,  also  called  a  "reactance"  coil,  Fig.  159, 
represents  what  might  be  called  magnetic  resistance.  If  an 
iron  core  consisting,  in  practice,  of  thin  sheets  of  metal,  be 
built  up,  and  one  of  the  in- 
sulated wires  of  an  alternating 
circuit  be  wrapped  a  number 
of  times  around  it,  as  shown, 
there  will  be  a  magnetic  kick 
or  reactance  set  up,  which 
will  have  the  effect  of  offer- 
ing resistance  to  current  flow. 
This  is  called  "magnetic  kick," 
or  "reactance."  The  practical 
effect  upon  current  flow  is 
essentially  the  same  as  that 
of  the  rheostat.  The  mag- 
netic field  set  up  around  the 
core  of  the  coil  has  the  effect 
of  creating  a  counter  E.  M.  F., 
which  opposes  the  line  voltage 
and  reduces  it.  The  choke 
coil  is,  however,  very  much 
more  economical  in  operation 
than  is  the  rheostat,  but  is  not 
nearly  so  satisfactory  for  the 
production  of  projection  light 
as  is  the  transformer  or  auto 
transformer,  largely  by  reason 
of  the  fact  that  it  has  a  ten- 
dency to  produce  flaming  at 
the  carbons,  and  where  it  is 
used  difficulty  is  found  in  con- 
centrating the  crater  into  a 
small  area.  The  transformer 
has,  of  course,  a  power  factor, 
but  I  hardly  think  any  good  purpose  will  be  served  by  going 
into  that  matter,  particularly  in  view  of  the  fact  that  the 
author  can  no  longer  recommend  the  use  of  operating  room 
transformers.  True  these  instruments  are  quite  efficient  and 
by  their  use  a  very  good  illumination  may  be  had.  Still, 
the  use  of  alternating  current  at  the  projection  arc  is  out  of 


sso 

Figure  160. 


348  MOTION    PICTURE    HANDBOOK 

date,  and  ought  to  be  entirely  discontinued.  Motor-gen- 
erator sets  and  mercury  arc  rectifiers  have  been  brought  to 
a  high  state  of  perfection,  so  there  is  now  no  good  reason 
why  alternating  current  should  be  used  for  projection  pur- 
poses, nor  is  its  use  efficient,  when  viewed  from  the  stand- 
point of  curtain  brilliancy.  By  this  I  mean  that,  whereas  it 
is  possible  to  secure  practically  as  excellent  an  illumination 
with  alternating  current  as  with  direct  current,  still  it  will 
take  practically  double  the  amperage  to  do  it.  In  fact,  for 
a  picture  of  given  size  a  better  screen  result  will  be  had 
with  25  amperes  D.  C.  than  with  50  amperes  A.  C.,  and 
in  order  to  get  the  same  result  in  illumination  as  that  pro- 
duced by  40  amperes  D.  C.  it  would  be  necessary  to  use 
fully  80  amperes  A.  C.  Therefore,  even  allowing  that  the 
transformer  has  a  higher  efficiency  than  the  rectifier  or 
motor-generator  set,  still  if  equal  screen  illumination  is  had 
it  will  cost  more  to  use  A.  C. 

Where  the  coils  are  wound  around  opposite  legs  of  the 
core,  as  in  Fig.  155,  the  transformer  is  called  a  "core" 
transformer;  where  the  coil  is  wound  around  the  central  leg 
of  the  core  (inside  the  outer  legs  of  the  core)  it  is  known 
as  the  "shell"  type,  Fig.  157. 

Please  let  it  be  understood  that  I  am  not  entering  into  all 
the  details  of  transformer  construction.  The  details  of  con- 
struction have  much  to  do  with  the  efficient  performance  of 
a  transformer,  but  all  I  seek  to  accomplish  in  this  article  is 
to  give  the  operator  a  fairly  comprehensive  understanding  of 
the  theory  upon  which  the  transformer  works — not  to  give 
him  instructions  enabling  him  to  build  one.  That  calls 
for  very  careful  calculations  and  experiment,  which  can  only 
be  made  by  a  duly  qualified  electrical  engineer. 

Transformers  may  be  built  to  deliver  current  to  a  three- 
wire  secondary  from  which  two  voltages  may  be  had;  for  in- 
stance, 220  and  110.  This  is  illustrated  in  Fig.  160.  As  a 
matter  of  fact  usually  alternating  current  three-wire  systems 
are  two-wire  circuits  up  to  the  transformer,  and  beyond  the 
transformer  become  three-wire  systems  merely  by  either  the 
peculiarity  of  construction  of  the  transformer  or  the  method 
of  hitching  up  two  transformers. 

The  operator  is  as  a  general  proposition  only  interested 
in  the  theory  of  the  transformer  and  the  practical  operation 
of  the  low  voltage  transformer  commonly  called  "compens- 
arc,"  "economizer,"  "inductor,"  which  ordinarily  takes  110 


FOR    MANAGERS    AND    OPERATORS 


349 


or  220  volts  supply  from  the  line  and  delivers  secondary  cur- 
rent at  arc  voltage,  and  this  is  the  type  of  transformer  to 
which  we  will  devote  our  attention. 

As  has  already  been  remarked,  volts  times  amperes  taken 
from  the  line  equals  volts  times  amperes  delivered  on  the 
secondary,  less  the  loss  in  the  transformer  which,  as  I  have 
already  remarked,  may  run  anywhere  from  10  to  20  per  cent. 

In  operating  a  projection  arc  lamp  it  is  necessary  at  times 
to  vary  the  amperes.     Now  the  secondary  of  a  transformer 
works    against    a   slight   resistance   of    the    secondary   circuit 
wires  and  a  considerable  re- 
sistance   of    the    projection 
arc,    therefore    the    current 
flow  against  this  particular 
fixed   resistance   can   either 
be    increased   or    decreased 
by  increasing  or  decreasing 
the  voltage  of  the  second- 
ary. 

As  has  already  been  re- 
marked, the  voltage  of  the 
secondary  will  depend  upon 
the  relative  number  of 
turns  in  the  primary  and 
the  secondary  coil.  The 
greater  the  number  of  turns 
in  the  primary  with  relation 
to  the  number  of  turns  in 
the  secondary  the  less  the 
voltage  of  the  secondary. 

It  is  a  known  fact  that 
the  best  voltage  across  an 
alternating  current  arc  is 
approximately  35  volts.  In 
order  to  keep  the  arc  burn- 
ing steadily  it  is  always 

necessary  to  have  a  steadying  resistance  or  a  reactance  in  the 
arc  circuit.  One  advantage  of  reactance  for  steadying  the  arc 
is  that  there  is  very  little  power  lost  in  the  reactance,  whereas 
with  resistance  all  of  the  steadying  effect  is  turned  into  heat, 
and,  therefore,  means  a  lot  of  lost  power.  Reactance  can  be 
obtained  only  on  alternating  circuits. 

In  order  to  change  the  current  at  the  arc  it  is  necessary, 
therefore,  to  change  the  steadying  reactance  when  using  a 


MAM 


Figure  161. 


350 


MOTION    PICTURE    HANDBOOK 


transformer  or  auto  transformer.  This  is  done  in  different 
ways.  In  some  cases  the  turns  in  the  primary  are  changed, 
and  in  this  way  the  reactance,  or  magnetic  choking,  is 
changed  so  as  to  change  the  value  of  current  at  the  arc. 

This  fact  is  taken  advantage  of  as  per  Fig.  161,  in  which 
A,  B,  C  are  buttons  and  D  ,a  lever  which  completes  the  cir- 
cuit of  the  primary  coil  through  one  of  these  buttons.  It 
will  readily  be  seen  that  if  lever  D  be  on  button  A  the  num- 
ber of  turns  in  the  primary  will  be  decreased,  and,  since  the 
turns  in  the  secondary  remain  fixed,  the  voltage  of  the  sec- 
ondary and  consequently  its  amperage  will  be  raised.  By 
moving  lever  D  to  button  B  or  C  the  number  of  turns  in 
the  primary  is  increased,  and,  therefore,  the  voltage  and 
amperage  in  the  secondary  is  decreased. 

Another  scheme,  used  in  the  Fort  Wayne  A.  C.  compensarc, 
is  to  have  small  additional  reactance  coils,  which  are  cut  in 
or  cut  out  of  circuit  by  means  of  a  switch.  These  are 
placed  in  the  secondary  circuit,  so  that  the  secondary  voltage 


Figure  162. 

remains  the  same  for  the  different  values  of  current,  and  this 
gives  the  same  length  of  arc  and  condition  of  the  crater  on 
the  different  steps.  See  Fig.  162. 


FOR   MANAGERS   AND   OPERATORS 


351 


Fusing  Projection  Circuits  Where  Transformer  is  Used. — 
Let  it  be  clearly  understood  that  the  term  "transformer," 
as  here  used,  means  the  low-voltage  transformer  commonly 
termed  "Economizer,"  "Inductor,"  "Compensarc,"  etc.  Be- 
fore reading  this,  however,  I  would  recommend  the  oper- 
ator to  turn  to  Page  343,  and  study  the  electrical  action  of 
these  devices. 

When  dealing  with  transformers  it  must  be  clearly  under- 
stood that  one  ampere  from  a  110  volt  line  becomes  con- 
siderably more  than  two  amperes  at  the  35  volt  projection 
arc,  and  that  one  ampere  from  a  220  volt  line  becomes  ap- 
proximately between  five  and  six  amperes  at  the  35  volt  arc. 
Let  it  also  be  clearly  understood  that,  for  the  purpose  of 
calculating,  we  assume  the  voltage  of  the  A.  C.  projection 
arc,  and  therefore  the  voltage  of  the  secondary  of  the  trans- 
former, to  be  35,  although  it  may  range  anywhere  between 
30  and  40. 

This  brings  about  a  peculiar  and  ap- 
parently very  little  understood  condition 
as  applied  to  fusing.  Almost  all  trans- 
formers (remember  I  am  speaking  of 
economizers,  etc.)  are  fused  on  their 
primary  side  only.  This  is  bad  practice. 

Fig.  163  is  the  diagrammatic  representa- 
tion of  a  transformer-controlled  projection 


Note. — Error:  Switch  7  should  be  between  fuses  1-1  and  transformer  3. 

Figure  163. 

circuit  in  which  1-1  are  the  fuses  at  the  beginning  of  the 
primary  circuit,  either  at  the  operating  room  distribution 
panel  or  the  main  house  switchboard,  as  the  case  may  be; 
2-2  are  the  lines  from  1-1  to  the  transformer;  3  is  the  trans- 
former; 4-4  the  lines  from  the  transformer  secondary  to 
fuses  5,  and  6-6  are  the  lines  from  secondary  fuses  5  to 
machine  table  switch  7.  All  these  may  be  rubber  covered 
wire,  but  lines  4-4  and  6-6  must  be  of  sufficient  size  to  ac- 


352  MOTION    PICTURE    HANDBOOK 

commodate  the  full  amperage  capacity  of  secondary  fuses. 
Line  2-2  should  not  be  less  than  No.  6  B.  &  S.,  and  it  would 
be  still  better  to  have  them  No.  4,  because  it  may  become 
necessary,  in  case  of  breakdown  or  for  some  other  reason, 
to  remove  the  transformer  and  substitute  a  rheostat,  in 
which  case  you  would  not  want  to  pull  less  than  50  or  60 
amperes,  and  No.  6  R.  C.  is  only  rated  at  50,  No.  5  at 
55,  and  No.  4  at  60  amperes. 

The  ordinary  procedure  is  to  install  wires  2-2  just  large 
enough  to  carry  the  secondary  capacity  of  the  transformer, 
but,  for  reasons  already  set  forth,  this  is  not  the  best  prac- 
tice. If  wires  4-4  and  6-6  are  rubber  covered,  then  No.  4 
must  be  used,  since  practically  all  transformers  (econo- 
mizers, compensarcs,  inductors,  etc.)  have  a  60  ampere  sec- 
ondary capacity,  but  if  wires  4-4  and  6-6  are  asbestos  covered, 
they  come  under  the  weatherproof  rating,  and  No.  6  is  large 
enough,  since  No.  6  weatherproof  is  rated  at  70  amperes. 
Wires  8-8,  from  machine  table  switch  to  lamp,  must  be 
asbestos  covered  stranded  No.  6,  unless  a  special  transformer 
delivering  more  than  a  70  ampere  secondary  current  is 
installed,  in  which  case  they  must  be  large  enough  to  ac- 
commodate the  current.  Fuses  1-1  are  merely  designed  to 
protect  wires  2-2  and  the  transformer  primary  coil,  but  inas- 
much as  No.  6  wire  will  accommodate  nearly  three  times  the 
primary  current  capacity  of  the  transformer,  they  really,  in 
effect,  protect  only  the  transformer  primary  coil,  and  for 
the  ordinary  economizer  delivering  a  maximum  of  60  am- 
peres at  the  arc,  they  should  be  30  ampere  capacity.  Some 
transformers  will  deliver  more  than  60  amperes  secondary, 
especially  if  the  voltage  be  a  little  higher  than  rated,  but 
you  will -find  that  30  ampere  fuses  will  meet  all  requirements. 
The  secondary  may  be  fused  to  65  amperes,  which  will  give 
a  5  ampere  leeway.  But,  however,  if  65  be  found  insufficient, 
no  harm  will  be  done  by  installing  others  of  70  ampere 
capacity. 

The  reason  for  requiring  fuses  on  the  secondary  as  well 
as  on  the  primary  are  twofold;  First,  some  operators  and 
managers  locate  the  transformer  outside  the  operating  room, 
even  putting  it  down  in  the  basement.  This  is  very  bad  prac- 
tice, but  nevertheless  they  do  it,  and  then,  exercising  still 
more  and  greater  bad  judgment,  stick  50  or  60  ampere  fuses 
on  the  primary.  The  inspector  is  not  likely  to  see  it,  because 
it  is  an  out  of  the  way  place.  For  practical  purposes  they  may 
just  as  well  not  fuse  at  all,  because  with  110  volt  transformers, 
60  ampere  primary  fuses  would  deliver  about  150  amperes  on 


FOR   MANAGERS   AND    OPERATORS  353 

the  secondary,  whereas  with  a  220  volt  supply  it  would 
give  nearly  300.  Second,  except  in  small  sizes,  cartridge  and 
plug  fuses  are  only  made  in  multiples  of  5  amperes,  that  is  to 
say  20,  25,  30,  35,  etc.  Now  with  a  110  volt  supply  30  ampere 
fuses  will  deliver  approximately  60  amperes  on  the  secondary, 
but  the  capacity  of  the  fuses  and  of  the  transformer  is  so 
nearly  :alike  that  there  might  be  trouble  with  30  ampere 
fuses  blowing.  If,  however,  you  install  others  of  35  ampere 
capacity,  the  next  size,  it  makes  a  possible  difference  of 
between  10  and  15  amperes  at  the  arc,  with  the  110  volt 
supply,  and  between  20  and  30  amperes  with  the  220  volt 
supply,  whereas  5  amperes  difference  in  the  fuses  on  the 
secondary  means  5  amperes,  and  no  more;  therefore  it  is 
possible  to  fuse  much  more  rationally  on  the  secondary  than 
it  is  on  the  primary. 

Compensarcs 

ALTERNATING  CURRENT  TYPE  A,  FORM  4 

This  device  is  manufactured  by  the  Fort  Wayne  Electric 
Works  for  use  on  alternating  current  circuits  only.  It  is 
self-contained  and  requires  no  auxiliary  rheostat  or  other 
controlling  mechanism.  Before  in- 
stalling the  compensarc  examine  the 
name  plate  to  see  if  the  rating  agrees 
with  the  frequency  and  line  voltage 
of  your  service. 

Place  the  compensarc  directly 
beneath  the  lamp  house  of  the  pro-i 
jection  machine  if  possible,  other- 
wise in  some  position  convenient 
to  the  operator  to  allow  him  to 
adjust  the  amperage  of  his  arc. 
Connect  both  wires  from  the 
Power  Company's  service  through 
a  double-pole*  fused  switch  to  the 
two  terminals  of  the  compensarc 
marked  "LINE."  Connect  two  ter- 
minals marked  "LAMP"  to  the  projec- 
tion arc  terminals  through  the 
double-pole  operating  switch  on  the 
projection  machine.  As  this  is  an 
A.  C.  device  there  are  no  positive  ^^^ 

or  negative  wires.  ^^p    Figure  164. 


354 


MOTION    PICTURE    HANDBOOK 


Fig.  165  is  a  diagram  of  connections  for  the  A.  C.  com- 
pensarc.  The  primary  or  line  wires  should  be  fused  to  about 
half  the  maximum  current  at  the  lamp.  This  would  ordi- 
narily require  about  a  30-ampere  fuse. 


Note. — This  diagram  supplied  by  the  manufacturer.  The  author 
does  not  agree  with  omitting  fuses  from  the  secondary  circuit. 
See  Fig.  163. 

Figure  165. 


This  device  is  adjustable  in  three  steps,  which  steps  have 
been  found  to  meet  the  general  service  conditions. 

When  the  switch  on  the  compensarc  is  open  no  current 
flows  through  the  lamp,  but  the  operator  should  not  handle 
his  carbons  without  opening  the  operating  switch  on  the  projec- 
tion machine,  because  if  the  outside  lines  have  a  ground  and  the 
operating  room  is  grounded  the  operator  can  receive  a  shock 
of  full-line  potential.  When  through  with  the  show  open  the 
primary  line  switch. 

Fig.  166  shows  the  slate  top  of 
the  A.  C.  compensarc  and  the 
switch  blade.  Throwing  the  switch 
blade  in  contact  with  the  first  clip 
of  the  switch  (Fig.  166)  gives  an 
adjustment  so  that  with  the  car- 
bons separated  about  three-six- 
teenth of  an  inch  the  current  flow- 
ing through  the  projection  lamp  Figure  166. 


FOR   MANAGERS   AND   OPERATORS  355 

will  be  approximately  30  amperes.  In  contact  with  the  sec- 
ond clip  of  switch  the  adjustment  changes  so  that  approxi- 
mately 40  amperes  flow  through  the  arc.  Throwing  the 
switch  blade  over  to  the  third  clip  allows  approximately  60 
amperes  to  flow  through  the  lamp.  The  manufacturer  recom- 
mends the  use  of  five-eighths-inch  cored  carbon  upper  and 
lower. 

In  order  to  determine  if  your  compensarc  is  in  good  con- 
dition on  all  three  steps,  first,  start  the  arc  on  any  one  of  the 
steps,  then  jump  the  switch  quickly  to  the  other  two  steps  in 
succession,  watching  the  light.  There  should  be  an  appre- 
ciable difference  in  the  light,  which  you  should  be  able  to  de- 
tect in  trying  this  several  times.  If  you  think  the  compens- 
arc is  heating  too  much  do  not  attempt  to  judge  the  tem- 
perature by  your  hand;  use  a  thermometer  on  the  hottest 
part.  Lean  the  thermometer  in  contact  with  the  hottest  part 
for  5  or  10  minutes  and  the  temperature  should  never  exceed 
40  degrees  C.  or  72  degrees  F.  above  the  room  temperature. 

To  obtain  the  best  results  carefully  observe  the  following: 

(1)  Make  sure  the  two  leads  marked  "lamp"  are  connected 
to  the  projection  arc  lamp  through  operating  switch  on  the 
projection  machine. 

(2)  Always  open  operating  switch  on  projection  machine 
when  changing  carbons,  to  eliminate  possibility  of  shock  due 
to  grounds  on  the  power  system. 

(3)  Connect  to   leads  marked  line  directly  to   the  power 
line    through    a    fused    double-pole    switch.    When    through 
using  the  compensarc  open  the  line  switch. 

(4)  Never  connect  any  resistance  in  series  with  the  com- 
pensarc either  on  the  line  or  lamp  side. 

(5)  Be  sure  the  line  voltage  and  frequency  agree  with  the 
voltage  and  frequency  marked  on  compensarc  nameplate. 

(6)  Be  sure   all  connections  are  perfectly  clean  and  tight 
and    see    that    adjusting    switch    has    not    been    damaged    in 
shipment. 

(7)  Do  not  try  to  use  any  more  current  than  is  required  to 
obtain  a  good  picture. 

(8)  Do  not  overload  your  carbons,  as  this  will  produce  a 
very  noisy  arc. 

(9)  Do   not   separate   carbons    too   far;    a    three-sixteenth- 
inch  separation  on  five-eighths  cored  carbons  will  give  good 
satisfaction  with  40  amperes. 


356 


MOTION    PICTURE    HANDBOOK 


Plate  1,  Figure  167. 


THE     EDISON     ECON- 
OMY TRANSFORMER 

The  Edison  Company 
claims  a  very  high  effi- 
ciency and  a  simple  ad- 
justing mechanism  for 
its  transformer,  which  is 
illustrated  in  Plate  1. 

Wiping  Connections. — 
The  device  has  five  leads 
entering.  At  one  side, 
directly  under  that  part 
of  the  top  in  which  the 
word  "Lamp"  is  cast,  are 
the  secondary  wires,  which 
are  to  be  connected  direct- 
ly to  the  arc  lamp,  either 
wire  to  either  lamp  bind- 
ing post. 


Plate  2,  Figure  168. 


FOR    MANAGERS    AND    OPERATORS 


357 


The  three  wires  entering  the  opposite  side  are  the  primary 
lines.  The  wires  directly  under  the  word  "Common"  must 
always  be  connected  to  one  side  of  the  line  switch.  One  of 
the  other  two  wires  should  be  connected  to  the  other  side  of 
the  line  switch,  but  which  one  is  to  be  so  connected  will  de- 
pend upon  the  line  voltage.  This  is  all  made  clear  in  Fig. 
168,  so  that  no  mistake  can  possibly  be  made.  The  end  of 
the  wire  not  in  use  must  be  carefully  wrapped  with  insu- 
lating tape  and  left  dead. 


To  Line 
Through 
Machine  Switch 


Common      TOO 


110 


CONNECTION  FOR 
105  VOLTS  Of?  LESS 


Fig.  A 


To  Line 
Through 
Machine  Switch 


Common        WO 


110 


CONNECTION  FOR 
108-1 10  OR  120  VOLTS 


Fig.  B 


*  II 


To  Line 

~~| 

c 

Common     200          220 

Fig.  C 

^--^xv>- 

To  Line 


Common      200       220 
Fig.  D 


Plate  3,  Figure  169. 

For  further  information  see  the  wiring  diagram  in  Fig. 
169,  which  gives  all  necessary  information  with;  regard  to 
both  the  110  volt  and  220  volt  transformer  connections. 

Range  of  Adjustments. — In  Plates  1  and  2  you  see  a  handle 
or  crank  on  top  of  the  transformer.  This  handle  operates 
adjusting  plugs  which  vary  with  the  current  at  the  arc.  Cast 
into  the  cover  on  top  of  the  transformer  case,  Plate  2,  are 


358 


MOTION    PICTURE    HANDBOOK 


two  arrows,  marked  respectively  "Raise"  and  "Lower." 
Turning  toward  "Raise"  you  will  raise  the  voltage,  and 
hence  the  amperage  at  the  arc;  the  opposite  direction  lowers 
the  voltage,  hence  the  amperage  at  the  arc.  The  crank  or 
handle  raises  or  lowers  leakage  plugs  in  the  magnetic  cir- 
cuit, the  same  being  placed  between  the  primary  and  second- 
ary windings,  thus  increasing  or  decreasing  the  strength  of 
the  magnetic  field. 


:  c> 


WEDGC 


LAMINATED    FRAME 


Plate  4,  Figure  170. 

The  primary  and  secondary  windings  are  secured  to  the 
iron  core  by  means  of  wooden  wedges,  as  per  Plate  4.  These 
wedges  must  be  tight  enough  to  hold  the  windings  rigid. 
If  the  windings  are  loose,  so  that  you  can  move  them  with 
your  hands  when  the  top  casting  is  removed,  then  the  wedges 
should  be  driven  tighter.  To  do  this  it  is  only  necessary  to 
remove  the  top  and  slip  some  thin,  blunt  instrument  down 
between  the  windings  and  the  frame  to  the  top  of  the  wedges 


FOR   MANAGERS   AND   OPERATORS  359 

and  drive  them  down  further.  Plate  4  shows  the  transformer 
with  the  top  cover  casting  removed.  To  remove  the  cover, 
take  out  the  four  round  head  screws  shown  in  Plate  2. 

The  Edison  transformer  is  claimed  by  its  manufacturers 
to  be  practically  noiseless  in  operation,  and  should  it  at  any 
time  become  noisy  there  are  three  adjustments  which  may 
require  attention:  (a)  The  nut  on  top  of  the  handle  (crank) 
may  have  become  loose.  The  screwshaft  to  which  this 
handle  is  attached  is  fitted  with  a  shoulder  below  the  cast- 
ing, and  between  this  shoulder  and  the  under  side  of  the  top 
casting  is  a  spring  washer.  It  is  necessary  that  the  nut  on 
top  of  the  handle  be  set  up  sufficiently  tight  to  compress 
this  washer  flat.  This  means  the  nut  should  be  set  up 
moderately  tight,  though,  of  course,  not  tight  enough  that 
the  handle  will  turn  too  hard,  (b)  The  leakage  plugs  are 
fitted  at  their  sides  with  phosphor  bronze  springs.  These 
springs  hold  the  plugs  rigid  between  the  walls  of  the  sup- 
porting guides.  Should  they  fail  of  this  purpose,  then  they 
must  be  bent  to  give  greater  tension,  (c)  The  thread  in  the 
shaft  to  which  the  handle  is  attached  should  make  a  good 
fit  in  the  crosspiece  to  which  the  plugs  are  fastened.  A  loose 
fit  at  this  point  will  not  make  the  transformer  exactly  noisy, 
but  may  cause  it  to  hum. 

Operation.— After  connecting  the  transformer,  close  the 
line  switch  and  the  operating  switch  and  strike  the  arc  in 
the  usual  way,  after  which  turn  the  adjusting  handle  until 
you  get  the  desired  result  on  the  screen.  This  will,  of 
course,  vary  with  size  of  the  picture,  .etc.  Under  varying 
conditions  it  may  be  necessary  to  work  with  the  handle 
clear  down  or  clear  up.  Ordinarily,  however,  a  position 
somewhere  midway  should  meet  the  requirements. 

POWER'S  INDUCTOR 

Power's  Inductor,  Fig.  171,  consists  of  a  well  insulated, 
strongly  clamped  laminated  core  with  the  primary  wound 
on  one  side  or  leg  of  the  core  and  the  secondary  on  the 
other.  The  casing  consists  of  a  cast-iron  front  and  back, 
with  a  perforated  brass  cover.  On  the  front,  at  the  top,  two 
wires  emerge,  underneath  which,  on  the  casting,  is  the  word 
"lamp."  These  two  wires  connect  directly  to  the  carbon 
arms  of  the  projector  lamp.  It  makes  no  difference  which 
wire  you  connect  to  the  upper  or  lower  carbon  arm.  At 
the  back  side,  near  the  top,  the  two  primary  leads  come  out. 
They  should  be  connected  to  the  supply,  as  per  Fig.  163, 


360 


MOTION    PICTURE    HANDBOOK 


Page  351.     On  the  face  of  the  front  casting  is  a  hand-wheel 

which   operates    a   single-pole    knife   switch,   located   on   the 

I       *          |  opposite   side   of  the   casting.     When 

I  I          I  I        this  switch  is  thrown  so  that  its  finger 

II  j        points  toward  "high"  you  are  getting 
II          j         the     maximum     amperage,     approxi- 
II          jjf          mately  65.     When   it  points   to   "me- 

3?r""T^feA»Hfc^  I  dium"    you     are     getting     a    medium 

amperage,  and  when  it  points  to  "low" 
you  are  getting  the  lowest  amperage 
the  transformer  will  supply. 

The  inductor  is  designed  for  a 
maximum  of  65  amperes  on  "high,"  54 
on  '"medium,"  and  45  on  "low"  when 
used  on  110  or  220  volts,  it  being,  of 
course,  understood  that  you  cannot 
use  110  volt  inductor  on  220,  or  a  220 
on  110.  In  other  words,  you  must 
have  an  inductor  suitable  to  the  vol- 
tage of  your  supply;  also  it  must  be 
Figure  1/1.  suitable  to  the  cycle  of  the  current 

you  use,  though  the  inductor  may  be  used  on  voltage  rang- 
ing 10  per  cent  below  to  10  per  cent,  above  that  for  which 
it  is  rated,  but  in  one  case  there  will  be  a  corresponding 
increase,  and  in  the  other  a  decrease  in  its  rated  amperage. 
The  inductor  is  designed  for  a  maximum  temperature  rise 
of  50  degrees  Fahrenheit  above  the  surrounding  atmosphere, 
and  ordinarily  its  temperature  will  not  exceed  30  degrees  in 
excess  of  the  surrounding  air.  It  occupies  12  x  14  inches  floor 
space,  is  19  inc'hes  high,  and  weighs  approximately  100 
pounds.  Its  efficiency  rating  will  compare  favorably  with 
other  machines  of  its  kind. 


THE  HALLBERG   ECONOMIZER 

The  "Hallberg"  A.  C.  to  A.  C.  economizer  is  nothing 
more  or  less  than  a  transformer  of  the  semi-constant  cur- 
rent type,  specially  designed  for  use  in  moving  picture 
projection  arc  circuits,  taking  A.  C.  at  line  voltage  and 
delivering  A.  C.  at  .arc  voltage.  "Semi-constant"  means 
that  it  will  receive  supply  at  a  fixed  potential,  but  will  de- 
liver at  the  arc  practically  steady  amperage  flow,  regardless, 
within  reasonable  limits,  of  the  length  of  the  arc. 

The  device  consists  of  a  continuous,  rectangular  core,  on 
one  leg  of  which  is  wound  a  primary  coil,  and  on  the  opposite 


FOR   MANAGERS   AND    OPERATORS 


361 


leg  a  secondary  coil,  the  latter  being  of  larger,  heavier  wire 
than  the  former,  to  which  the  arc  lamp  is  connected. 

In  Fig.  165  we  have  a 
view  of  the  top  of  the 
Hallberg  Economizer 
showing  the  various 
taps  coming  out.  The 
two  marked  "to  lamp" 
are  the  terminals  of  the 
secondary  coil,  which 
attach,  through  fuses, 
to  the  arc  lamp,  as  per 
Fig.  163.  The  terminal  Figure  172. 

marked  "1,"  Fig.  172,  is 

the  constant,  and  must  always  be  connected  to  one  side  of  the 
source  of  supply.  Either  one  of  terminals  "2"  "3,"  or  "4,"  Fig. 
172,  may  be  connected  to  the  other  side  of  the  supply,  according 
to  the  supply  voltage  and  the  amperage  desired  at  the  arc. 
Terminal  "4"  represents  one  end  of  the  primary  winding, 
of  which  terminal  "1"  is  the  other  end.  A,  B,  C  are  fuse 
receptacles,  and  leads  "2"  and  "3"  are  taps  connecting  to 
the  primary  coil  as  per  Fig.  154,  Page  342.  Now  if  a  fuse  plug  of 
sufficient  capacity  to  carry  the  primary  current  be  placed  in 
receptacle  C,  receptacles  A  and  B  being  empty,  then  as  you 
will  readily  see,  the  whole  of  the  primary  coil  will  be  in  use. 
This  connection  is  designed  for  use  where  the  primary  voltage 
is  a  little  above  normal,  or  when  you  require  the  lowest  am- 
perage the  economizer  will  deliver.  If  the  fuse  be  removed 
from  C  and  placed  in  A,  then  several 
turns  of  the  primary  coil  will  be  cut  out, 
which  will  have  the  effect  of  boosting 
the  secondary  voltage,  and  hence  the 
amperage  at  the  arc.  The  fuse  plug 
should  be  in  receptacle  A  when  the  line 
voltage  is  a  little  below  normal,  or  when 
the  highest  available  amperage  is  de- 
sired at  the  arc.  CAUTION:  Do  not 
unscrew  the  fuse  plug  while  the  arc  is 
burning.  If  you  do  the  current  will  arc 
and  burn  out  your  fuse  receptacle ;  other- 
wise this  arrangement  is  cheap,  practical, 
and  should  never  give  trouble. 
Fig.  173  shows  the  appearance  of  the  Hallberg  economizer. 
The  machine  table  switch  should  always  be  on  the  line  side  of 
the  economizer. 


i*. 


Figure  173. 


362  MOTION    PICTURE    HANDBOOK 

The  economizer  is  supplied  for  voltage  ranging  from  100 
to  120  and  200  to  220,  and  may  be  constructed  for  25,  35,  40,  50, 
60,  120,  and  up  to  140  cycles.  The  110  volt  economizer  lines 
are  usually  connected  to  terminals  1  and  2  when  the  voltage  is 
100  to  105;  to  1  and  3  between  105  and  115,  and  to  1  and  4 
if  between  115  to  120.  If  it  be  a  220  volt  economizer  then 
connect  to  1  and  2  for  220  volt  supply  and  to  1  and  4  for  240. 

The  manufacturer  supplies  the  following  data  for  the  Hall- 
berg  economizer. 

Line  fuses          Line  Line          Line  watts  Amperes 

required.        Voltage.  Amperes.      per  hour.  at  arc. 

Regular  Type — 30-40  Amperes. 

20                110  18                 1,400  30-40 

10                 220  9                 1,400  30-40 

Standard  Type— 45-55  Amperes. 

30                110  25                 1,800  45-55 

15                 220  13                 1,800  45-55 

Special  Type — 60-80  Amperes. 

40                 110  35                 2,200  60-80 

20                 220  18                 2,200  60-80 

Searchlight  Type— 125-150  Amperes. 

80                 110  75                4,200  125-150 

40                 220  35                4,200  125-150 

There  are  four  types  of  this  device,  viz:  the  "Regular," 
the  "Standard,"  the  "Special,"  and  the  "Searchlight."  The 
Regular  type  is  designed  for  stereopticon  and  very  light 
motion  picture  theatre  work,  where  the  picture  is  small  and 
the  performance  not  continuous. 

The  Standard  type  is  recommended  by  the  manufacturer 
for  ordinary  motion  picture  theatre  performances.  It  delivers 
a  maximum  of  approximately  60  amperes  at  the  arc. 

The  Special  type  is  made  for  those  who  desire  an  amperage 
in  excess  of  60,  and  is  size  the  author  recommends  to  those  who 
want  brilliant  screen  illumination. 

The  Searchlight  type  was  ordinarily  designed  for  Kinema- 
color  work,  but  it  is  now  offered  to  the  regular  motion  pic- 
ture trade.  It  has  a  maximum  capacity  of  150  amperes. 

Where  the  Searchlight  is  used  it  is  well  to  use  either  three- 
quarter  or  seven-eighth  inch  cored  carbons.  Where  the 
Special  and  Searchlight  economizers  are  used  the  asbestos 
covered  cable  should  be  No.  4  for  the  Special,  and  No.  2 
for  the  Searchlight.  For  all  other  economizers  they  should 
be  No.  6. 


FOR   MANAGERS   AND    OPERATORS  363 

FREDDY   ECONOMIZER 

The  Freddy  Economizer,  the  general  appearance  of  which 
is  shown  in  Plate  1,  manufactured  by  Walter  G.  Preddy, 
San  Francisco,  consists  primarily  of  two  parts,  viz.,  a  heavy 
laminated  sheet  metal  core,  16  inches  in  length,  around  which 
is  placed  a  winding  consisting  of  two  layers  of  No.  4  magnet 
wire.  The  first  or  inner  layer  is  wound  directly  over  the  core, 
but  insulated  therefrom.  The  second,  or  outer  layer  is  wound 
over  the  first,  and  has  brass  taps  brought  out  on  every 
seventh  turn.  These  taps  are  so  arranged  that  the  windings 
may  be  tapped  at  eleven  points,  thus  providing  for  a  greater 
or  less  amount  of  inductance,  according  to  the  number  of 
amperes  it  is  desired  to  use  at  the  arc.  The  taps  are  labeled 
"contacts"  in  Plate  2,  the  wire  terminating  in  an  arrow 
head,  labeled  "clamp,"  connecting  to  one  of  the  contacts. 
The  two-screw  connection  at  the  top  of  the  coil,  and  the 
brass  tap  at  the  same  end,  are  at  the  extreme  ends  of  the 
windings,  all  other  taps  being  interposed,  and  acting  to 
cut  in  or  out  a  certain  number  of  turns  of  wire,  thus  varying 
the  inductive  effect,  and  hence  the  amperage  at  the  arc. 


Plate  1,  Figure  174. 

The  Preddy  Economizer  is  an  economy  coil,  inductance  coil, 
reactance  coil,  or  choke  coil,  those  names  meaning  the  same 
thing  and  applying  equally  to  the  same  apparatus.  The 
more  familiar  term  is  choke  coil.  There  are  no  switches  or 
levers  to  manipulate;  all  the  regulation  is  perfected  by  means 
of  the  clamp  and  contacts,  Plate  2,  as  already  described. 
The  connector  (clamp)  is  merely  a  slotted  brass  casting 
that  slips  on  the  taps,  and  is  then  screwed  tight  by  hand. 
CAUTION:  Never  use  pliers  in  making  this  connection. 

Directions. — The  Preddy  Economizer  is  not  a  transformer 
or  auto-transformer,  and  has  no  "primary"  or  "secondary" 


364 


MOTION    PICTURE    HANDBOOK 


winding.  It  is  connected  into  the  arc  lamp  circuit  precisely 
the  same  as  you  would  connect  a  rheostat.  See  B,  Fig.  142, 
in  which  just  substitute  a  Freddy  coil  for  rheostat  C.  It 
is  advisable  to  use  (manufacturer's  recommendation)  wire 
not  smaller  than  No.  6,  and  fuses  not  smaller  than  75  amperes. 
There  is  no  reason  for  placing  fuses  on  the  lamp  side  of  the 
Freddy  Economy  Coil,  as  is  advisable  with  the  transformer, 
since  the  amperage  is  the  same  on  both  sides  of  the  Freddy 
device. 

Never  attach  the  economizer  to  a  metal  lined  wall  unless  you 
first  remove  the  metal  or  place  a  marble  or  other  insulating  or 


Flate  2,  Figure  175. 


non-metallic  material  of  substantial  thickness  between  the  econo- 
mizer and  the  metal.  If  the  device  be  attached  to  a  metal 
lined  wall  or  set  on  a  metal  lined  floor  there  will  be  a  vibra- 
tion set  up  in  the  metal,  which  will  cause  a  more  or  less 
loud  buzzing  sound.  The  manufacturer  recommends  that 
fairly  hard  cored  carbons  be  used  in  connection  with  this 
device,  both  top  and  bottom.  The  tap  connection  giving  the 
highest  amperage  is  the  one  opposite  the  tube  connector. 


FOR   MANAGERS   AND    OPERATORS 


365 


If  a  dissolver  is  to  be  used  with  one  economy  coil  the  two 
lamps  must  be  wired  in  series.  See  "The  Stereopticon." 

When  using  the  economizer  do  not  add  rheostats  to  the  cir- 
cuit, or  switches  for  regulating,  or  other  devices.  Schemes 
of  this  kind  often  cause  a  great  deal  of  trouble,  for  which 
the  instrument  gets  the  blame. 

The  economizer  is  a  very  sturdily  built,  rugged  device, 
Which  ought  to  last  indefinitely  if  given  reasonable  care.  It 
is  well  insulated  and  will  not  "bake  out,"  owing  to  the  extra 
heavy  insulation  between  the  core  and  winding,  as  well  as 
between  the  layers. 

THE  FORMOSTAT 

The  formostat,  which  is  widely  used  and  well  liked  on  the 
Pacific  Coast,  and  somewhat  known  throughout  the  Middle 
West,  is  of  the  auto  type  of  transformer.  Its  ratio  is  two  to 
one  for  110  volt  current  and  4  to  1  in  the  220  volt  type — that  is 


Figure  176. 

to  say,  one  ampere  taken  from  110  volt  line  becomes  two  on 
the  secondary,  while  one  ampere  taken  from  the  220  volt  line 
becomes  four  on  the  secondary.  Its  range  of  adjustment  is 
from  30  to  65  amperes,  and  its  construction  is  quite  simple, 
there  being  two  wires  for  the  line  and  two  for  the  lamp. 
These  leads  are  marked  with  paper  tags,  when  the  formostat 


366  MOTION    PICTURE   HANDBOOK 

is  purchased.  In  case  the  tags  are  absent  the  two  large 
leads  should  be  connected  to  the  lamp  and  the  two  smaller 
one  to  the  feed  wires.  The  adjustment  is  made  in  divisions 
of  about  4  amperes  and  without  in  any  way  disturbing  the  arc. 
In  Fig.  176  we  see  a  sectional  front  and  side  view,  A  and  B 
being  the  line  wires  and  1  and  2  the  coils.  The  regulation 
of  amperage  is  secured  by  raising  or  lowering  the  top  coil. 
In  Fig.  177  we  have  a  view  of  the  formostat.  At  the  top 
is  a  notched  rack  upon  which  hangs  a  wire  loop;  from 
this  loop  is  suspended  coil  1,  Fig.  176.  By  lowering  coil  1, 
a^^ ^^^  or  in  other  words,  drop- 

ping the  wire  loop  to  a 
lower  notch  in  the  rack, 
amperage  is  increased, 
or  by  raising  it  the  am- 
perage is  lowered.  The 
winding  on  the  110  volt 
formostat  is  of  No.  5 
wire,  and  as  the  instru- 
ment is  of  the  auto  type 
this  is  equivalent  to  two 
No.  5  wires  in  parallel, 
so  that  in  fact  each  No. 
5  wire  has  only  to  carry 
32^  amperes.  In  the  220 
volt  type  the  winding  is 
of  No.  4  and  No.  8 
wires,  and  at  full  load 
the  No.  4  carries  43  and 
the  No.  8  17  amperes, 
respectively.  A  110  volt 
formostat  works  well  on 
any  voltage  from  105  to 
125;  and  the  220  volt 
177  machine  operates  suc- 

cessfully at  from  210  to 
240  volts.  The  makers  recommend  that  the  formostat  be  placed 
on  the  floor  under  the  lamphouse.  Connect  the  wires  marked 
"line,"  which  are  the  smaller  of  the  four  wires,  to  the  line 
through  30  ampere  fuse  and  switch.  Connect  the  two  leads 
marked  "lamp"  directly  to  the  lamp.  The  formostat  makers 
recommend  that  there  be  no  switch  between  the  formostat  and 
the  lamp,  but  that  it  be  placed  on  the  line  side.  All  wire  con- 
nections should  be  soldered,  unless  some  good  type  of  wire 
connector  is  used;  see  D,  Figure  30,  Page  89. 


FOR   MANAGERS   AND   OPERATORS 


367 


Wiring  Diagrams  for  the  Formostat. — Fig.  178,  No.  1, 
shows  the  connections  used  with  the  regular  110  volt  formo- 
stat  supplying  two  lamps  alternately.  No.  2  shows  connec- 
tions used  with  110  volt  formostat  for  three  lamps.  That  is  to 


2  2.0  VOLT  L//VE 

30  (\MP.  SWTCH 

AND  FUSE. 


Figure  178. 

say,  a  motion  picture  arc  and  a  dissolver.  No.  3  shows  con- 
nections used  with  special  220  volt  formostat  for  two  lamps, 
and  No.  4  shows  connections  used  with  special  220  volt 
formostat  for  three  lamps. 


368  MOTION    PICTURE    HANDBOOK 

The  tags  on  the  wires  are  marked  A,  B,  C  and  D,  in  the  110 
volt  type,  and  AA  prime,  B,  €,  D,  on  the  220  volt  tags.  If 
it  is  desired  to  use  the  110  volt  formostat  with  connections  as 
per  No.  1  and  2,  Fig.  178,  the  leads  will  first  have  to  be 
selected  by  testing  between  the  line  and  lamp  leads  with  110 
volt  lamp.  Between  two  of  these  wires  will  be  found  no 
voltage  and  these  wires  are  line  A  and  lamp  C,  therefore  the 
two  remaining  are  line  B  and  lamp  D.  This  test  must,  of 
course,  be  made  with  the  current  on.  If  it  is  desired  to  use 
connections  No.  3  or  No.  4,  Fig.  178,  with  the  220  volt  formo- 
stat, put  out  before  the  beginning  of  1912,  the  wires  will  have 
to  be  changed,  and  this  the  manufacturer  will  do,  free  of 
charge.  The  change  cannot  be  made  outside  of  the  manu- 
facturer's shop,  and  should  not  be  attempted. 


Motor  Generator  Sets 

General  Instructions. — There  are  certain  instructions 
which  apply  alike  to  all  motor  generator  sets,  rotary  con- 
verters and  other  devices  of  like  nature.  To  incorporate 
these  instructions  in  the  matter  covering  each  individual  set 
would  consume  valuable  space  needlessly,  therefore,  they 
have  been  incorporated  under  the  head  of  General  Instruc- 
tions. 

General  Instruction  No.  1. — Locating  the  Motor  Gener- 
ator. In  locating  a  motor  generator  or  rotary  converter, 
several  things  must  be  taken  into  careful  consideration. 
Wherever  practical  it  is  much  better  to  locate  the  machine 
either  in  the  operating  room  or  a  room  directly  adjoining  and 
connecting  therewith. 

A  basement,  particularly  if  damp  or  dark,  is  objectionable 
for  installations  of  this  kind.  Where  there  is  dampness  the 
insulation  of  the  wires  will  absorb  more  or  less  moisture, 
which  will  be  expelled  rapidly  when  the  machine  warms  up, 
and  this,  many  times  repeated,  is  likely  to  produce  injurious 
results.  The  most  serious  objection  is  that  in  case  anything 
goes  wrong  it  takes  much  longer  to  investigate  and  make 
the  repair,  if  a  repair  is  possible,  than  it  would  if  the  machine 
were  located  in  or  adjoining  the  operating  room.  Still  an- 
other objection  to  basement  locating  lies  in  the  fact  that 
basements  are  usually  more  or  less  dark,  which  entails  the 
making  of  repairs  and  performing  other  operations  entirely 
by  artificial  light. 


FOR    MANAGERS   AND    OPERATORS  369 

The  only  legitimate  objection  to  locating  machines  of  this 
kind  in  or  adjoining  the  operating  room  lies  in  the  possible 
vibration  and  noise  or  the  weakness  of  the  floor. 

As  a  general  proposition  it  may  be  said  that  any  floor  too 
weak  to  carry  a  machine  of  this  kind  is  unfit  to  be  the  floor 
of  an  operating  room.  Vibration  can  be,  to  all  intents  and 
purposes,  eliminated  by  means  of  felt,  as  per  instructions 
under  "Installation." 

When  practical,  always  set  your  motor  generator  out  far 
enough  from  the  wall  so  that  you  can  walk  all  around  it, 
and  before  your  floor  is  put  down  have  the  conduits  laid, 
so  as  to  carry  the  connecting  wires  underneath  the  floor. 

This  is  a  little  extra  expense  and  labor,  but  in  the  long 
run  it  pays,  and  pays  big. 

If  you  do  locate  your  generator  in  the  basement  it  is  a 
good  plan  to  place  it  on  a  pedestal  or  platform  raised  some 
distance  from  the  floor,  particularly  if  there  is  any  danger 
of  the  basement  at  any  time  containing  water.  The  frame 
of  the  machine  should  be  thoroughly  grounded  by  means  of 
a  copper  wire,  one  end  of  which  must  make  good  electrical 
contact  with  the  frame  and  the  other  with  a  water  pipe  or 
the  earth,  as  described  under  "Grounds,"  Page  259.  Also 
select  as  light  a  spot  as  possible,  if  any  daylight  enters  the 
basement. 

If  the  machine  is  located  in  the  basement,  make  your 
operating  room  leads  of  ample  size.  It  won't  cost  much 
more,  and  there  will  be  less  waste.  The  size  of  the  leads 
will,  of  course,  depend  on  the  amperage  they  are  to  carry, 
and  their  length.  In  this  connection  see  Pages  42  and  45. 

General  Instruction  No.  2. — Installation.  As  soon  as  a 
new  machine  is  unboxed,  the  name  plate  should  be  carefully 
inspected.  If  it  be  a  D.  C.  to  D.  C.  machine,  you  have  only 
to  ascertain  that  the  volts  marked  on  the  motor  name  plate 
correspond  with  your  line  voltage.  If  it  be  an  A.  C.  to  D.  C. 
machine,  then  the  volts,  cycles  and  phase  must  agree  with 
those  of  the  circuit  on  which  it  is  to  be  used.  The  name 
plate  marking  will  also  indicate  the  volts  and  amperes  for 
the  arc  lamp,  and  due  care  should  be  taken  that  the  am- 
perage rating,  as  indicated  by  the  name  plate,  be  not  ex- 
ceeded to  any  considerable  extent,  except  for  short  periods 
of  time. 

If  the  motor  generator  is  mounted  on  a  sub-base  which 
it  is,  for  any  reason,  necessary  to  dispense  with,  great  care 
must  be  exercised  that  the  motor  and  generator  be  perfectly 


370  MOTION    PICTURE   HANDBOOK 

lined  with  each  other,  else  there  will  be  undue  strain  on  the 
coupling  of  the  two  shafts.  Failure  to  perfectly  line  the 
shafts  will  probably  result  in  noise,  vibration  and  a  rapid  wear 
at  both  the  coupling  and  bearings.  Machines  in  which  the 
armature  of  the  motor  and  generator  are  mounted  on  one 
shaft,  with  but  three  bearings,  and  no  coupling  between, 
should  never  under  any  circumstances  be  installed  without 
their  sub-base,  if  they  are  of  the  type  that  uses  a  sub-base. 
Where  a  motor  and  generator  .are  locked  together,  on  a 
sub-base  or  otherwise,  it  is  not  necessary  to  bolt  them 
down  solidly  to  the  floor  (it  is  not  necessary  to  build  foun- 
dations for  machines  of  this  character),  and  if  the  machine  is 
located  in  the  operating  room  or  in  an  adjoining  room  it  is 
not  desirable  to  do  so.  The  best  plan  is:  Have  a  sheet 
metal  pan  made,  one  to  two  inches  deep  and  sufficiently 
large  to  contain  the  base  of  the  machine  and  extend  out 
under  the  oil  boxes.  Procure  heavy  felt — the  kind  that  is  from 
one-half  inch  to  one  inch  thick,  if  you  can  get  it,  and  cut 
enough  to  make  a  pile  at  least  4  inches  thick,  cutting  the 
pieces  about  3  inches  larger  than  the  base  of  the  machine. 
Place  the  felt  where  you  propose  to  locate  the  machine,  lay 
the  pan  on  top  of  it  and  set  the  machine  in  the  pan.  No  bolts 
or  fastenings  of  any  kind  are  necessary.  If  the  machine  does 
not  set  on  the  felt  without  giving  trouble  the  armatures  are 
not  properly  balanced  and  the  machine  should  go  back 
to  the  factory.  The  idea  of  the  felt  is  to  absorb  all  the 
vibration  and  prevent  its  being  communicated  to  the  floor 
and  the  walls  of  the  building.  It  renders  the  machine  to  all 
intents  and  purposes  noiseless. 

Caution. — Where  direct  connected  motors  and  generators 
are  joined  to  each  other  by  a  flexible  connection  on  the 
shaft,  and  not  placed  on  a  single,  rigid  iron  base,  then  the  pad 
proposition  does  not,  of  course,  apply.  Such  an  outfit  must 
be  bolted  down  on  a  solid  foundation.  After  the  machine  has 
been  on  the  pad  a  week,  carefully  level  it,  if  necessary,  by 
slipping  sheets  of  metal  under  the  low  side.  //  is  very  necessary 
that  the  armature  be  perfectly  level  endwise,  else  it  will  not 
"float"  (have  end  play),  and  failure  to  float  will  probably  pro- 
duce grooved  bearings  and  commutator. 

Having  the  machine  located,  revolve  the  armature  by  hand 
to  make  sure  it  revolves  freely.  Examine  the  armature  and 
commutator  carefully  to  see  that  they  are  not  bruised.  Let 
the  oil  out  of  the  oil  wells  and  fill  them  up  with  fresh  oil. 
(See  General  Instruction  No.  3.)  The  electrical  connections 


FOR   MANAGERS   AND   OPERATORS 


371 


should   be   made   by   an   electrician,   who    should   follow   the 
wiring  diagram  sent  with  the   machine. 

General  Instruction  No.  3. — Oil.  The  much  advertised 
patent  oils  are  absolutely  unfit  for  motor  or  generator  lubri- 
cation. If  you  use  them  you  are  more  than  likely  to  either 
have  trouble  with  the  bearings,  or  a  comparatively  frequent 
and  unecessary  expense  for  bearing  renewal,  to  say  nothing 
of  worn  journals. 

The  character  of  oil  to  be  used  will  depend  considerably 
upon  climatic  conditions.  In  the  South,  where  it  is  always 
comparatively  warm  and  much  of  the  time  summer  heat, 
I  would  recommend  the  same  oil  used  for  generators  in 
the  local  electric  light  plant.  The 
superintendent  of  the  plant  will  tell 
you  what  it  is,  and  no  doubt  will  sell 
you  oil  at  a  reasonable  figure.  You 
cannot  do  any  better,  because  oil 
used  to  lubricate  heavy  generator 
bearings  is  necessarily  an  excellent 
lubricant,  and  you  can  rest  assured 
the  light  plant  has  the  oil  best  suited 
to  local  climate.  In  the  Middle 
North,  I  would  recommend  a  medium 
heavy  dynamo  oil  for  summer  use; 
it  may  be  used  the  year  round  if  the 
generator  is  in  a  room  that  is  kept 
warm  in  winter,  but  if  in  an  unheated 
place  a  light  dynamo  oil  will  be 
found  to  give  the  best  satisfaction  in 
winter.  In  the  extreme  North  a 
medium  oil  in  summer  and  a  light 
dynamo  oil  in  winter  will  be  best. 

Caution. — Most,  if  not  all,  motor  generator  sets  have  the 
oil  carried  up  to  the  journals  by  rings  which  rest  on  the 
journals  and  revolve  merely  by  the  friction  of  their  own 
weight  on  the  journal,  as  per  Fig.  179,  which  shows  the 
oil  ring  resting  on  the  journal,  revolving  through  a  groove 
in  the  babbit  bearing.  Now,  you  will  readily  see  that  if  too 
heavy  an  oil  be  used  in  winter  time,  and  the  machine  be 
located  where  it  is  very  cold,  the  oil  will  congeal  and  stop 
the  ring  from  revolving,  in  which  case  no  oil  would  be  fed 
to  the  journal  and  there  would  be  trouble.  There  are 
grooves  cut  in  the  babbit  bearing  to  facilitate  oil  distribution. 

Be  sure  your  oil  is  free  from  dust  or  sediment.  Never 
leave  oil  standing  open.  If  you  do  it  will  collect  dust  and 


Figure  179. 


372  MOTION    PICTURE    HANDBOOK 

the  lubricating  quality  of  the  oil  will  be  very  greatly  impaired. 
Dirty  oil  is  often  the  cause  of  bearings  heating. 

General  Instruction  No.  5. — Cleanliness.  It  is  important 
that  all  parts  of  motor  generators  be  kept  scrupuluosly  clean. 
Oil  should  not,  under  any  circumstances,  be  allowed  to  col- 
lect, either  on  the  machine  or  on  the  floor  near  it,  and  the 
machine  should,  so  far  as  possible,  be  kept  free  from  dust. 
A  medium  size  hand  bellows  will  be  found  very  convenient 
for  removing  dust  from  the  armature,  from  around  the  pole 
pieces  and  in  other  inaccessible  places.  A  dirty  machine  is 
evidence  of  a  lazy,  indifferent  of  incompetent  operator. 

General  Instruction  No.  6. — Loose  Connections.  It  is 
highly  important  that  all  electrical  connections  and  all  bolts 
and  nuts  be  inspected  periodically  and  carefully  tightened 
up,  and  all  electrical  connections  be  kept  not  only  tight  but 
perfectly  clean.  Loose  connections  are  a  continual  source  of 
absolutely  unnecessary  trouble. 

General  Instruction  No.  7. — Ammeter  and  Voltmeter.  All 
motor  generators  are  or  should  be  provided  with  both  volt- 
meters and  ammeters,  and  they  should  by  all  means  be  located 
on  the  wall  in  front  of  the  operator  as  he  sits  in  operating 
position.  It  is  a  serious  mistake  to  install  a  voltmeter  and 
ammeter  in  an  out  of  the  way  place.  They  should  be  con- 
stantly under  the  operator's  eyes,  since  there  are  points  at 
which  the  arc  furnishes  maximum  illumination  with  minimum 
current  consumption,  and  with  the  ammeter  directly  in  front 
of  him  the  operator  soon  learns  where  he  gets  the  most 
light  with  the  least  current  consumption  and,  if  he  is  a 
capable  man,  keeps  his  arc  at  that  point. 

General  Instruction  No.  8. — Care  of  the  Commutator.  The 
commutator  of  a  direct  current  motor  or  generator  ought 
to  require  very  little  care,  but  sometimes  does  require  a  great 
deal. 

The  best  evidence  the  commutator  is  in  Al  condition  is 
a  sort  of  glazed  appearance,  smooth  as  glass,  a  brownish 
shade  in  color  and  a  slight  squeak  from  the  carbon  brushes 
when  the  armature  is  revolved  slowly.  To  obtain  and 
maintain  this  condition  the  following  care  must  be  given: 

(a)  The  brushes  kept  set  as  nearly  as  possible  at  the 
sparkless  point,  which  point  may,  with  the  old  style  gener- 
ator lacking  the  inner  or  "commutator"  pole,  vary  with  the 
load.  On  the  newer  type  of  generator  the  inner  or  commu- 


FOR   MANAGERS   AND    OPERATORS  373 

tating  pole  is  used  and  the  manufacturer  marks  the  point 
at  which  the  brush  yoke  should  be  set  by  making  either  a 
chisel  or  center-punch  mark  on  the  yoke  and  on  the  frame. 
Some  manufacturers  fill  these  marks  with  white  paint  so 
they  are  very  easily  seen — some  do  not.  Where  these  marks 
are  present  the  brush  yoke  should  always  be  set  so  that  the 
marks  on  the  frame  casting  and  the  yoke  coincide,  or,  in 
other  words,  are  opposite  each  other! 

(b)  The    brushes    must    have    just    sufficient    tension    to 
make  good  electrical  contact  with  the  commutator,  remembering 
that  every  particle  of  unnecessary  pressure  will  tend  to  unduly 
wear  both  commutator  and  brushes,  and  to  groove  the  copper 
unless   the  armature  has  a  little  end  play. 

(c)  That   the    commutator   be   kept   clean   and   free   from 
dust.    This  may  best  be  accomplished  by  cleaning  the  whole 
machine  every  day,   blowing  the  dust  out  from  around  the 
field  poles,  etc.,  with   a  bellows,   and  last  of  all,  wiping  off 
the  commutator  with   a  canvas   pad  made  as   follows:     Cut 
a    piece    of    ordinary    canvas    6    inches    square,    fold    this    so 
that    it    is    2    inches    wide    by    6    inches    long,    which    will 
form  a  pad  with  a   face   of   one   thickness,   backed   by  two 
thicknesses.    Next  open  up  the  pad  and  smear  a  little  vaseline 
on  the  center  section,  which  is  the  ^back  side  of  the  face  of 
the  pad,  after  which  refold,  let  lie 'a  few  hours  in  a  warm 
place,  and  it  is  ready  for  use.    Sufficient  vaseline  will  gradually 
soak  through  the  pad  to  give  the  commutator  all  the  lubrica- 
tion it  needs,  and  that  is  mighty  little.     The  foregoing  'holds 
good  in  summer,  and  in  winter,  too,  if  the  generator  is  located 
in  a  warm  .room,  but  if,  on  the  other  hand,  the  machine  is 
cold,  then  it  will  be  well  to  moisten  the  face  of  the  pad  by 
using  a  few  drops   of  a  very  thin   oil   on   a  piece   of  glass, 
spreading  it  around  evenly  and  then  wiping  it  off  on  the  face 
of  the  pad,  the  idea  being  to  get  the  oil  evenly  distributed 
on  the  pad.     Remember  this,  however,   too   little  lubrication  is 
better  than   too  much,  and  heavy  lubricants    (thick  oils)    must 
never,  never,  NEVER  be  used  on  a  commutator.     If  one  applica- 
tion as  above  every  six-hour  run  does  not  suffice,  then  it  is 
likely   that,    (1)    your   brushes    have   too  much    tension,    (2) 
your  machine  is  overloaded,  (3)  your  brushes  not  properly  set 
or    (4)    there  is   some   other   trouble.     Never  use  gasoline   or 
benzine  around  a  commutator;  it  is  likely  to  attack  and  soften 
the  shellac  and  insulation  and  thus  set  up  serious  trouble. 

Caution. — Where  the  mica  insulation  of  the  commutator  is 
undercut  great  care  should  be  taken  in  regard  to  the  lubricat- 


374  MOTION    PICTURE   HANDBOOK 

ing  of  the  commutator,  and  if  a  soft  brush  is  used  no  lubrica- 
tion should  be  given.  This  caution  is  necessary  with  under- 
cut insulation  by  reason  of  the  fact  that  the  lubricating 
medium  will  have  a  tendency  to  combine  with  carbon  dust 
and  fill  up  the  space  between  the  commutator  bars,  thus  in 
time  possibly  short  circuiting  the  bars.  Also  where  soft 
brushes  are  used  the  brushes  themselves  as  a  rule  contain 
sufficient  paraffine  to  provide  all  necessary  lubrication. 

(d)  See  to  it  that  sufficient  oil,  or  combined  oil  and  carbon 
dust,  has  not  collected  at  any  point  or  spot,  either  on  the 
commutator  or  face  of  any  brush,  to  form  a  semi-insulation: 

(e)  That   there   are   no   high   or   low   bars  and   that   the 
commutator  is  perfectly  round. 

(f)  That  a  fragment  of  copper  does  not  drag  across  the 
insulation  between  two  adjacent  bars,  or  that  oil  and  carbon 
dust  does  not  form  such  a  bridge.     This  fault  will  be  evi- 
denced by  a  thin,  sparkling  ring  of  light  around  the  commu- 
tator. 

(g)  That  the  brush  springs  do  not  carry  sufficient  current 
to  heat  them. 

(h)  That  the  brushes  fit  properly  in  their  holders,  and 
are  kept  free  from  accumulation  of  dirt,  dust,  etc.  They  should 
be  taken  out  and  cleaned  once  in  every  60  hours  run. 

(i)     That  the  brushes  are  neither  too  hard  nor  too  soft. 

(j)  That  the  armature  "floats"  slightly,  i.e.,  has  from  one- 
sixteenth  to  one-eighth  inch  end  play,  according  to  size  of 
machine.  This  tends  to  prevent  the  brushes  from  cutting 
grooves  in  the  commutator;  is  very  important.  Unless  the 
machine  sets  perfectly  level  the  armature  will  not  "float,"  hence 
a  level  setting  is  important. 

(k)  That  the  copper  and  mica  insulation  wear  down 
evenly. 

(1)  That  the  generator  is  not  overloaded,  and  that  there 
are  no  other  faults  present  which  would  tend  to  cause  un- 
necessary sparking,  or  otherwise  injure  the  commutator. 

Should  the  brushes  of  the  motor  or  generator  shpw 
excessive  sparking,  it  might  be  attributed  to  one  of  the 
following  causes; 

(a)  If  a  belt  driven  machine,  the  belt  may  be  slipping; 
if  the  sparking  is  spasmodic  or  intermittent,  the  trouble  will 
probably  be  found  in  the  belt,  since  belt  slip  causes  sudden 


FOR   MANAGERS   AND    OPERATORS 


375 


variations  in  speed,  and  this  will,  in  itself,  cause  sparking, 
since  it  has  the  effect  of  producing  heavy  fluctuations  in  the 
voltage.  The  remedy,  of  course,  is  to  tighten  the  belt,  or 
use  a  belt  dressing,  and,  in  this  connection,  ordinary  black 
printer's  ink  is  as  good  an  article  as  I  know  of  to  stop  belt 
slipping,  and  ten  cents  worth  obtained  at  any  printer's  will 
last  for  a  month  or  more. 


Plate  1. 


Plate  2. 


Figur     180. 


(b)  Brushes  not  set  correctly,  that  is  to  say,  the  rocker 
arm  too  far  one  way  or  another;  also  the  brushes  may  be 
too  close  together  or  too  far  apart.  In  the  first  case  the 
remedy  is  to  move  the  rocker  arm  until  the  neutral  position 
is  found,  whereupon  sparking  will  either  cease  or  be  reduced 
to  a  negligible  quantity.  If  this  fails  to  remove  the  trouble  I 
would  then  see  if  the  brushes  themselves  are  the  correct 
distance  from  each  other.  In  a  two-pole  machine  they  should 
bear  on  the  commutator  at  diametrically  opposite  points. 
That  is  to  say,  the  distance  from  brush-point  to  brush-point 
should  be  exactly  the  same  when  measured  both  ways 
around  the  commutator;  in  other  words,  distance  A  should 
equal  distance  B,  ,as  per  1,  Fig.  180.  If  it  be  a  four-pole 
machine  *  with  two  positive  and  two  negative  brushes  (four 
altogether)  the  correct  distance  to  set  them  is  one-fourth  of 
the  circumference  of  the  commutator  between  the  points 
of  adjacent  brushes,  that  is,  distances  marked  X  should  all 
be  equal,  as  per  2,  Fig.  180.  If  it  be  a  mc*chinv,  with  more 
than  two  positive  and  two  negative  brushes  (more  than 


376  MOTION    PICTURE    HANDBOOK 

four  brushes  all  told),  divide  the  number  of  commutator 
segments  by  the  number  of  poles,  or  field  coils  of  the  machine; 
the  result  will  equal  the  distance,  in  commutator  bars,  the 
brushes  should  be  apart. 

(c)  Dirty  brushes  or  dirty  commutator  may  cause  spark- 
ing, and  may  even  prevent  the  generator  from  picking  up  its 
load  at  starting,  and  will  sometimes  cause  a  badly  fluctuating 
arc.     Some  of  the   causes   of  dirty  brushes  and   dirty  com- 
mutator  are    as    follows:      Carbon   brushes    contain    a   small 
amount  of  paraffine.     When  the  carbon  gets  warm  this  par- 
affine,  if  excessive  in  quantity,  is  likely  to  ooze  out  and  coat 
the  commutator,  thus  partially  insulating  it  in  spots,  or  the 
paramne  may  mix  with  dust  and  coat  the  end  of  the  brush 
with     a     semi-insulating     compound.       If     copper     brushes 
be   used   they   may  become   clogged   with   a   mixture  of  oil 
and   dust;  the   obvious   remedy  is  to  clean   the  dirty   parts. 
To  clean  the  commutator,  use  a  brush  stiff  enough  to  remove 
any  foreign  matter  which  may  cling  to   the  surface  of  the 
commutator,  yet  not  stiff  enough  to  injure   the  surface.     If 
the    brush   will   not   remove    the   deposit,,  then   use    00   sand 
paper  (never  use  emery  paper  or  emery  cloth  on  a  commutator) 
applying  the   same  while  the   commutator   is   revolving,   but 
with  just  barely  enough  pressure  to  clean  the  metal.     After 
having   cleaned    the    surface,   put   a   few   drops    of    light   oil 
on   a   cloth,   or   use   the  pad  already   described   and   hold    it 
lightly  to  the  commutator  as  it  revolves.     Don't  get  much 
oil  on  the   surface  of  the   commutator — just   a  "suspicion," 
as  it  were.     If  it  is  a  carbon  brush  which  is  dirty,  or  which 
does  not  fit  the  curve  of  the  commutator,  raise  it  just  enough 
to  slip  a  piece  of  fine  sand  paper   (^  or  No.  1)  between  the 
brush  and  commutator,  with  the  sand  side  against  the  brush, 
and  pull  it  back  and  forth  around  the  curve  of  the  commu- 
tator until   enough   of  the   brush   has  been   ground  away   to 
clean  the  surface,  or  to  make  it  fit  the  commutator.     Be  sure 
and  always  clean  the  commutator  thoroughly  after  doing  this, 
since  if  carbon  dust  is  left  adhering  to  its  surface  it  may  work 
into  the  insulation  and  cause  a  local   short  circuit  between 
two   bars.     If  the  brush  is   made   of  metal   take  it  out  and 
clean  it   thoroughly  with  gasoline,  trimming  the   edges   and 
corners  off  with   a  file   if  necessary. 

(d)  The  brush  not  making  proper  contact  with  the  com- 
mutator, which  may  be  due  to   (1)  tensioij  spring  not  being 
strong  enough;    (2)    tension   spring  having   lost   its   temper; 
(3)  brush  stuck  in  its  holder;  (4)  brush  not  fitting  the  curve 


FOR   MANAGERS   AND    OPERATORS  377 

of  the  surface  of  the  commutator;  (5)  brush  holder  set  at 
the  wrong  angle;  (6)  high  bar  or  insulation.  The  remedies 
are:  (1)  Stretch  the  spring,  if  it  is  a  spiral  spring,  or  if  it 
is  not  a  spiral  spring,  do  whatever  is  needful  to  make  the 
spring  stronger,  installing  a  new  one,  if  necessary;  (2)  put 
in  a  new  spring,  and,  since  the  fact  that  the  old  spring 
has  lost  its  temper  is  evidence  that  the  spring  itself  is  carry- 
ing too  much  current,  reinforce  it  with  a  current-carrying 
jumper;  (3)  the  remedy  is  obvious:  do  whatever  is  needed 
to  loosen  .the  brush;  (4)  use  sand  paper,  as  before  described, 
until  the  brush  fits  the  commutator  surface;  (5)  straighten 
the  holder;  (6)  see  section  f,  further  on. 

There  should,  however,  be  only  sufficient  tension  on  the 
brush  to  insure  its  making  good  contact  with  the  commutator. 
Be  careful,  therefore,  and  don't  get  your  springs  too  strong. 
If  you  do  there  will  be  unnecessary  wear  both  on  the  brush 
and  the  commutator,  and  this  will  to  some  extent  add  the 
element  of  mechanical  heat  generated  by  undue  friction. 

The  reasons  for  the  brush  sticking  in  the  holder  are: 
(1)  Dirt  in  the  holder  or  on  the  brush;  (2)  brush  not  true;  (3) 
hammer  that  rests  on  the  brush  (where  this  type  of  tension 
is  used)  not  working  true  on  the  slot-end  of  the  brush.  The 
brush  should  slip  freely  in  its  holder,  though  not  freely 
enough  to  allow  of  any  considerable  amount  of  play,  and 
the  hammer  should  be  so  adjusted  that  it  lies  true  in  the  slot 
at  the  end  of  the  brush.  A  brush  which  is  not  true  may  be 
evened  up  by  tacking  No.  1  sand  paper  on  a  perfectly  flat 
surface  and  rubbing  tihe  brush  thereon. 

(e)  Commutator    worn    too    thin.      If    the    commutator 
wears   down   too   much,   although   it   may   wear    evenly   and 
appear   to   be   in   good   condition,   the   brushes   will   spark   in 
spite  of  everthing  you  may  do,  particularly  when  the  machine 
is  working  at  capacity.    The  reason  might  lie  in  the  fact  that 
since  the  segments  are  wedge  shape,  as  they  wear  down  they 
become  narrower,  thus  allowing  the  brush   to  span  more  of 
the  circumference  of    the  commutator  than  was  intended,  or 
there   might  be  a   slight   error   in   the  setting  of   the   brush 
holder,    and    this    error    becomes    greater    as    the    distance 
between    the    brush    holder    and    the    commutator    increases. 
The   only   remedy  is   a   new   commutator,   but   the   sparking 
may  possibly   be   lessened    somewhat   by   moving  the   brush 
holder  closer  to  the  commutator.     This   trouble  appears  at 
its  worst  in  a  series  type  machine. 

(f)  A  high  or  low  commutator  segment.     This  fault  may 


378  MOTION    PICTURE   HANDBOOK 

usually  be  detected  by  the  clicking  sound  made  by  the  brush 
in  passing  over  the  defective  segment.  When  the  segment 
is  low  the  brush  rides  in  toward  the  shaft  each  time  the  bad 
bar  passes  under  it.  If  it  is  high  the  brush  will  jump.  The 
remedy  will  depend  somewhat  upon  the  cause.  It  may  be 
that  the  segment  has  become  loose,  in  which  case  the  bar 
may  be  driven  back  into  place  by  tapping  lightly  with  a 
wooden  mallet,  or  by  using  a  wooden  block  and  hammering 
gently,  but  the  armature  will  probably  have  to  be  taken 
out  and  sent  to  the  repair  shop,  unless  you  yourself  can 
tighten  the  clamp  ring — a  rather  delicate  operation.  If  the 
segment  is  high  by  reason  of  the  fact  that,  being  of  harder 
material  than  its  mates  it  has  worn  down  more  slowly,  then, 
using  a  fine  file  it  may,  with  great  care,  be  dressed  down. 
If,  on  the  other  hand,  it  is  low,  then  the  only  remedy  is  to 
turn  down  the  rest  of  the  bars  to  match.  If  the  fault  is 
slight  this  may  be  done  by  re'moving  the  brushes  and  holding 
a  piece  of  grindstone  which  has  been  turned  out  to  fit  the 
circumference  of  the  commutator  to  it  while  it  is  revolved 
rapidly.  This  process  is,  however,  slow.  The  best  way  is 
to  put  the  armature  in  a  lathe  and  turn  it  off.  The  grinding 
may,  in  the  case  of  a  motor,  however,  be  done  with  the 
brushes  down  and  the  machine  running  by  its  own  power, 
but  if  this  is  done  it  should  be  done  with  great  caution. 
When  you  are  through  the  face  of  the  brushes  should 
be  thoroughly  cleaned  by  drawing  No.  J^  sand  paper 
around  the  curve  of  the  commutator  with  the  sand  side 
next  to  the  brushes  in  order  to  grind  off  their  face,  and 
thus  remove  any  particles  of  sand  which  may  have  become 
embedded  in  the  brush,  since  it  would  scratch  the  commu- 
tator and  cause  undue  wear.  It  is  better  to  do  the  grinding 
with  the  brushes  raised  and  the  machine  run  from  some 
outside  source  of  power  where  it  is  practicable. 

(g)  A  rough  or  eccentric  commutator.  This  may  be 
caused  by  improper  care,  or  by  the  use  of  defective  materials 
in  its  construction.  A  rough  commutator  may  be  detected 
merely  by  feeling.  The  mica  insulation  between  the  seg- 
ments will  either  stand  out  in  ridges,  or  be  worn  down  so 
that  there  is  a  small  groove  between  the  segments.  An 
eccentric  commutator  may  most  readily  be  detected  by  hold- 
ing some  instruments  firmly  against  the  frame  opposite  the 
commutator,  so  that  its  ends  just  touch  the  bars.  If  the 
commutator  is  true  it  will  touch  all  the  way  round  as  the 
armature  is  slowly  revolved,  but  if  the  commutator  is  eccentric 
it  will,  of  course,  only  touch  the  high  spots.  If  the  eccentric 


FOR   MANAGERS   AND    OPERATORS  379 

be  bad  it  will  cause  the  brushes  to  move  in  and  out  of  their 
holders  perceptibly  when  the  armature  is  revolved  slowly. 
The  only  remedy  is  to  turn  the  commutator  down,  and  this 
can  only  be  sucessfully  done  in  a  machine  shop  where  work 
of  this  character  is  understood. 

(h)  Brushes  having  too  high  resistance,  the  evidence  of 
which  is  that  they  get  very  hot  and  slowly  crumble  away 
at  the  end  next  to  the  commutator.  The  remedy  is  to  get 
good  brushes. 

(i)  Low  bearings.  In  some  types  of  machines  low  bear- 
ings will  throw  armature  out  of  center  sufficiently  to  distort 
the  magnetic  field,  and  this  will  cause  sparking.  The  evi- 
dence of  this  fault  is  that  the  air  gap  between  the  armature 
and  the  pole  piece  will  be  smaller  at  the  botttom  than  at  the 
top.  The  only  remedy  it  to  replace  the  worn  bearings  with 
new  ones. 

(j)  A  short-circuited  armature  coil.  This  trouble  will 
cause  the  voltmeter  to  fluctuate  badly,  and  the  shorted  coil 
to  heat  very  quickly.  The  coil  may  be  shorted  within  itself, 
or  there  may  be  a  connection  between  two  adjoining  com- 
mutator segments.  Remedy:  locate  and  remove  the  short. 

(k)  A  reversed  armature  coil.  This  may  be  located  by 
holding  a  compass  over  each  coil  of  the  armature  in  turn,  and 
sending  a  direct  current  through  the  coil,  with  the  brushes 
raised  and  resistance  in  series;  or  current  from  a  battery 
may  be  used.  The  coil  which  causes  the  compass  to  turn 
in  the  opposite  direction  from  its  mates  is  the  guilty  party. 
The  remedy  is,  reverse  the  connection  or  direction  of  the 
windings  of  the  defective  coil. 

(1)  A  bent  armature  shaft.  This,  of  course,  will  cause 
the  whole  armature  to  wobble.  The  only  practical  remedy  is 
a  new  shaft. 

(m)  Overload.  The  most  prominent  symptom  of  over- 
load is  the  armature  heating  all  over.  Sparking  may  be 
lessened,  but  not  entirely  stopped,  by  moving  the  brushes 
aihead  or  'back.  By  "ahead"  I  mean  in  the  direction  in  which 
the  armature  is  revolving.  The  remedy  is  obvious.  Get  a 
machine  of  larger  capacity,  or  cut  down  the  load  on  the  one 
you  have. 

(n)  High  speed  sparking  is  caused  by  the  brushes  not 
being  able  to  make  proper  connection  with  the  commutator  by 
reason  of  excessive  armature  speed. 

(o)  A  weak  field.  This  may  be  detected  in  a  generator 
by  its  inability  to  pick  up  readily,  and  by  failure  to  maintain 
normal  voltage.  On  a  motor  the  starting  power  is  decreased, 


380  MOTION    PICTURE    HANDBOOK 

but  the  speed  and  current  are  increased.  A  weak  field  may 
be  caused  by  (1)  a  loose  joint  in  the  magnetic  circuit;  (2) 
heat  may  lower  the  insulation  of  the  field  winding  sufficiently 
to  allow  the  current  to  short  circuit  through  it;  (3)  there 
may  be  a  metallic  short  in  the  field  coil.  Remedies:  With 
at  voltmeter  test  across  each  field  coil;  the  one  showing 
the  least  drop  is  the  defective  one.  If  all  read  the  same, 
then  there  is  a  loose  joint  in  the  magnetic  circuit. 

(p)  A  shaky  foundation,  or  anything  else  that  causes 
vibration  in  the  machine  will  set  up  commutator  sparking. 
The  only  remedy  is  to  eliminate  the  vibration. 

Should  a  ring  of  fire  develop,  or  something  that  looks  like 
a  ring  of  fire,  around  the  commutator,  it  may  be  caused  by 
(a)  a  piece  of  copper  pulled  across  the  insulation  between 
two  bars:  (b)  an  open  circuit  in  the  armature. 

In  the  first  instance  the  ring  will  not  be  strong,  but  just 
a  thin  sparkling  streak  of  light  around  the  commutator.  The 
remedy  is  to  remove  whatever  is  causing  the  short  between 
the  bars,  which  can  usually  be  done  by  holding  a  piece  of 
fine  sand  paper  lightly  to  the  commutator,  though  the  right 
way  is  to  stop  the  machine  and  hunt  up  the  trouble,  using 
a  magnifying  glass  if  necessary.  An  open  circuit  in  the 
armature,  however,  might  be  caused  by  reason  of  a  break  in 
one  of  the  armature  wires  itself,  or  in  one  of  its  connections 
with  the  commutator,  and  these  in  turn  may  be  caused 
by  excessive  current  burning  off  one  of  the  wires,  or  a  nick 
in  one  of  the  wires  may  be  the  seat  of  the  trouble,  or  the 
commutator  may  become  loosened  and  break  off  one  or 
more  of  the  leads.  The  defect  may  be  readily  located,  as 
the  mica  will  be  eaten  away  from  between  the  commutator 
segments  to  which  the  faulty  coil  is  connected,  and  the 
segments  themselves  will  become  full  of  holes  and  burned 
at  the  edges.  If  this  trouble  is  caught  in  time  the  open  may 
be  closed  and  the  commutator  turned  up  true.  Sometimes, 
by  reason  of  carlessness,  abuse  or  overload,  the  armature 
becomes  hot,  and  this  causes  the  solder  on  the  connections 
between  the  coils  and*  commutator  bars  to  soften,  where- 
upon centrifugal  force  will  throw  it  out,  and  there  will,  of 
course,  be  trouble,  though  there  is  no  complete  opening  of 
circuits'.  The  action,  however,  so  far  as  the  ring  of  fire  be 
concerned,  is  the  same  as  if  there  were,  and  the  commutator 
bars  will  become  blackened  and  pitted  and  their  edges 
burned.  But  if  any  of  the  foregoing  faults  be  caught  in 
time  they  can  be  remedied;  if  not  it  will  be  necessary  to  ' 


FOR   MANAGERS   AND    OPERATORS  381 

install  a  new  commutator,  and  perhaps  a  new  armature  coil 
as  well. 

General  Instruction  No.  9. — Before  starting  the  machine 
see  that  it  is  perfectly  clean  and  that  the  brushes  move 
freely  in  their  holders  and  make  good  contact  with  the  com- 
mutator. Also  make  sure  that  all  connections  are  tight. 

General  Instruction  No.  10. — Bearings  Run  Hot.  The  first 
rule  when  a  bearing  runs  hot  is  to  see  that  the  oil  well  is 
filled  with  good  clean  oil  and  that  the  oil-rings  run  freely, 
carrying  the  oil  to  the  shaft.  If  the  bearing  runs  hot  on 
a  new  machine  shut  down  and  wash  out  the  bearing  with 
kerosense.  Trouble  is  probably  due  to  dirt  that  has  accumu- 
lated in  shipment.  If  the  bearing  has  been  running  along 
satisfactorily  and  suddenly  gets  hot,  flood  the  well  with 
clean  oil,  leaving  the  drain  cock  open  and  pouring  in  the 
clean  oil  while  the  machine  is  running  to  free  the  bearing 
from  dirt.  A  change  to  a  different  grade  of  oil,  either 
heavier  or  lighter,  will  often  correct  a  bearing  trouble  of 
this  kind.  NEVER  USE  WATER  TO  COOL  A  BEARING,  it  may  get 
into  the  insulation  of  the  windings  and  cause  a  worse  trouble. 
A  machine  with  clean  oil  of  the  proper  grade  never  gives 
trouble  from  hot  bearings. 

General  Instruction  No.  11. — Heating.  Many  operators  who 
are  handling  motor  generator  sets  and  find  them  getting 
rather  warm  become  unduly  alarmed.  Excessive  heat  is,  of 
course,  not  only  bad,  but  dangerous  to  the  insulation.  How- 
ever the  fact  must  be  taken  into  consideration  that  the 
temperature  of  operating  rooms  frequently  reaches  between 
35  and  40  degrees  Cent.  The  American  Institute  of  Electrical 
Engineers  allows  a  temperature  rise  of  50  degrees  Cent.  (90 
degrees  Fahr.)  above  surrounding  atmosphere,  this  being 
based  on  40  degrees  (72  degrees  Fahr.)  atmospheric  temperature. 
Therefore,  simply  because,  in  a  hot  operating  room  one 
cannot  hold  his  hand  on  the  iron  of  the  machine  with  com- 
fort, it  does  not  follow  that  the  temperature  is  dangerous. 
A  thermometer  ought  always  to  be  used  to  determine  such  mat- 
ters. If  the  thermometer  does  not  register  a  temperature  rise  of 
say  more  than  30  or  35  degrees  above  the  surrounding  atmos- 
phere (Centigrade),  you  need  have  no  uneasiness.  To  change 
Centigrade  temperature  to  Fahrenheit  temperature  multiply 
the  degrees  Cent,  by  9/5  and  add  32.  For  instance:  opera- 
ting room  temperature,  40  Cent.  What  is  it  Fahr.?  40X9/5 
=  40-4-5  =  8X9  =  72  +  32=104  degrees  Fahr. 


382  MOTION    PICTURE    HANDBOOK 

FORT  WAYNE  A.  C.  TO  D.  C.  AND  D.  C.  TO  D.  C. 
COMPENSARCS       . 

General    Description.— Both    A.    C.    to    D.    C.    and    D.    C. 

to  D.  C.  compensarcs  are  what  are  commonly  styled  "motor 
generator  sets,"  that  is  to  say,  two  machines  coupled  to- 
gether, one  being  a  motor  and  the  other  a  generator.  In 
the  A.  C.  to  D.  C.  compensarcs  the  motor  and  generator  are 
mounted  on  a  common  base,  as  shown  in  Plate  No.  1. 
Fig.  181.  The  motor  and  generator  frames  of  the  D.  C.  to 
D.  C.  compensarcs  are,  however,  coupled  together  by  a 
common  flange,  as  shown  in  Plate  No.  2,  Fig.  181,  so  that 
no  base  is  necessary.  All  Fort  Wayne  compensarcs  are 
shipped  completely  assembled,  and  require  only  proper  in- 
stallation, filling  of  the  bearings  with  oil  and  proper  elec- 
trical connection  to  the  supply  and  lamp  circuits  (See 
General  Instruction  No.  2,  Page  369)  before  putting  into 
service. 


Plate  1.  Plate  2. 

Figure  181. 

The  A.  C.  to  D.  C.  compensarc  consists  -of  a  standard 
induction  motor,  either  single,  two  or  three  phase,  the  same 
being  directly  connected  to  a  special  D.  C.  generator.  The 
armature  shafts  of  the  set  are  joined  by  couplings,  and 
there  are  but  three  bearings,  two  on  the  motor  and  one  on 
the  generator.  The  generator  end  of  this  set  is  wound 
specially  for  use  with  projection  arc  lamps,  and  the  winding 
is  such  that  no  steadying  resistance  is  necessary  between 
the  arc  and  generator. 

While  the  115  and  220  volt  D.  C.  compensarcs  are  commonly 
referred  to  as  "motor  generator  sets,"  rightly  speaking  they 
are  not,  since  electrical  connections  are  different  from 
the  true  motor  generator  set.  The  machine  is  in  effect  a 


FOR   MANAGERS   AND   OPERATORS  383 

"balancer."  The  500  volt  D.  C.  compensate  is,  however,  a 
true  motor  generator,  the  motor  having  no  electrical  con- 
nection with  the  generator.  The  generator  end  of  the  D.  C. 
compensarc  has  exactly  the  same  characteristics,  as  that  of  the 
A.  C.  to  D.  C.  machine,  and  will  handle  the  arc  without 
any  steadying  resistance  interposed.  The  two-lamp  outfits 
use  a  steadying  resistance  during  the  time  of  changing  from  one 
lamp  to  the  other  only,  during  which  period  both  arcs  are 
burning  simultaneously.  The  generator  end  of  both  A.  C. 
to  D.  C.  and  D.  C.  to  D.  C.  compensarcs  have  practically 
the  same  mechancial  construction. 

The  D.  C.  compensarc  has  a  fan,  protected  by  a  metal 
guard  for  the  safety  of  the  operator,  mounted  on  the  shaft 
between  the  two  machines.  This  fan  rotates  with  the  shaft 
and  sets  up  a  current  of  air  which  helps  keep  both  motor  and 
generator  cool. 

Installation. — See   General   Instruction   No.  2. 

Oil. — See   General  Instruction   No.  3. 

Removing  Sub-Base  to  Install. — See  General  Instruction 
No.  2  and,  in  addition,  dowel  pins  are  provided  in  the  base 
of  the  generator  end.  To  remove  these  pins  hold  the  squared 
head  of  the  pin  with  a  wrench  and  tighten  up  the  nut,  which 
will  pull  out  the  pin.  Be  very  careful  that  any  liners  found 
under  the  feet  of  the  motor- or  generator  be  carefully  replaced 
in  their  original  position.  Should  the  coupling  be  taken  apart 
it  must  be  very  carefully  reassembled,  making  sure  that  the 
chisel  marks  on  the  rim  register  with  each  other. 

A.  C.  to  D.  C.  compensarcs  should  never  be  run  on  circuits 
where  the  variation  of  either  frequency  or  voltage  from  normal 
exceeds  5  per  cent.  Where  both  frequency  and  voltage  vary  the 
sum  of  the  variation  must  not  exceed  8  per  cent. 

Size  of  Fuses. — The  lamp  side  of  these  machines  does  not 
require  fusing,  since  the  generators  automatically  protect 
themselves  against  overload  current  when  the  arc  is  short 
circuited. 

The  motor  side  of  the  various  machines  should  be  fused  as 
follows: 

D.  C.  Compensarcs. 

50  amp.  1-lamp  and 

2-35  amp.  lamps  2-50  amp.  lamps 

35  amp.  1-lamp  alternately  alternately 


115   volt — 30   amp.   fuses  60  amp.   fuses  100  amp.  fuses 

230  volt — £0  amp.    fuses  40   amp.   fuses  60  amp.  fuses 

550  volt — 10    amp.   fuses  20  amp.   fuses  30  amp.  fuses 


384 


MOTION    PICTURE    HANDBOOK 
A.  C.  Compensates. 


35  amp.  1-lamp 


50  amp.  1-lamp  and 
2-35  amp.   lamps 
alternately 


2-50  amp.  lamps 
alternately 


125  amp.  fuses 
60  amp.  fuses 
60  amp.  fuses 
30  amp.  fuses 
50  amp.  fuses 
30  amp.  fuses 


The   wires    should   be   of   sufficient    size    so   that   the   line 
drop   from   the   machine    to   the   lamp    will   not   exceed    one 


Single  Phase 
110   volt  —  35 
Single  phase 
220    volt  —  20 
Two-phase 
110   volt  —  >20 
Two-phase 
220   volt  —  10 
Three-phase 
110    volt—  20 
Three-phase 
220   volt—  1  2 

amp. 
amp. 
amp. 
amp. 
amp. 
amp. 

fuses 
fuses 
fuses 
fuses 
fuses 
fuses 

80 
40 
40 
20 
50 
25 

amp. 
amp. 
amp. 
amp. 
amp. 
amp. 

fuses 
fuses 
fuses 
fuses 
fuses 
fuses 

Plate  3. 


Plate  4. 


Figure  182. 


volt  (see  Page  45)  or  2  per  cent,  of  the  voltage  when  the 
machine  is  delivering  full  load  current  to  the  lamp.  If 
wires  of  too  small  diameter  be  used  the  lamp  will  be  robbed 
of  some  of  its  amperage  and  give  poor  light. 

Electrical  Connections.— The  D.  C.  to  D.  C.  Compensarcs 
for  115,  230  and  500  volts,  one  lamp  outfits,  are  connected  as 
shown  in  Plate  No.  3,  Fig.  182,  while  those  for  the  two 
lamp  outfits  are  connected  as  shown  in  Plate  No.  4,  Fig. 


FOR   MANAGERS   AND    OPERATORS 


385 


182.  The  connections  for  the  A.  C.  to  D.  C.  two  lamp  com- 
pensarc  is  shown  in  Plate  No.  9,  Fig.  183,  while  those  for  the 
one  lamp  outfits  are  connected  as  shown  in  Plate  No.  8, 
Fig.  183. 


Plate  8. 


Plate  9. 


Figure  183. 


Internal   Connection   Diagram,    115-230  Volt 
D.  C.  to  D.  C.  Compensarc. 


Plate  12,  Figure  184. 


386  MOTION    PICTURE    HANDBOOK 

The  diagrams  shown  in  Plates  3,  4,  8,  and  9,  which  are 
the  external  connections  for  the  different  types  of  compens- 
arcs,  are  practically  the  only  ones  the  operator  will  have 
occasion  to  refer  to,  since  all  internal  connections  are  care- 
fully made  before  the  machine  is  tested  at  the  factory,  and 
are  as  they  should  be  when  the  operator  receives  the  machine. 


Internal  Connection  Diagram,  500  Volt 
D.  C.  to  D.  C.  Compensate. 

Plate  5,  Figure  185. 


It  is  only  in  exceptional  cases  that  some  trouble  inside 
the  machine  necessitates  the  opening  of  the  internal  con- 
nections. In  such  cases  Plates  5,  6,  7,  and  12  should  be 
referred  to  in  reconnecting. 

It  is  recommended  that  one  of  the  steel  panel  switch- 
boards, Plate  10,  especially  designed  for  use  with  the  com- 
pensarc,  be  included  in  each  compensarc  installation.  It  will 
not  only  facilitate  the  wiring  of  the  set,  but  help  serve  the 
purpose  of  General  Instruction  No.  7,  which  see. 

Starting  D.  C.  to  D.  C.  Compensates. — To  start  the  D.  C. 
to  D.  C.  compensarc,  with  projection  machine  switch  open, 
close  the  switch  in  the  main  line,  whereupon  armature  will 
begin  to  slowly  rotate,  in  a  counter-clockwise  direction  as 
you  face  the  generator  commutator.  Proper  direction  of  rota- 
tion is,  indicated  by  the  small  arrow  on  the  bearing  housing. 


FOR    MANAGERS    AND    OPERATORS  387 

Next  move  lever  of  starting  box  slowly  to  right  as  machine 
speeds  up,  until  it  finally  reaches  the  last  contact,  where  it 
will  be  caught  and  held  by  the  cut-out  magnet.  By  this  time 
the  armature  will  have  reached  maximum  speed. 

The  field  rheostat  of  the  generator  field  circuit  is  marked 
with  a  small  white  arrow  to  indicate  proper  position  it  should 
occupy  for  machine  to  deliver  the  current  and  voltage  at  the 
arc  as  shown  on  generator  name  plate. 

To  Start  Arc. — When  the  armature  is  up  to  speed,  arc 
may  be  struck  as  follows:  Close  projection  machine  switch 
and  bring  carbons  of  lamp  together,  instantly  separating  them 
again  about  one-sixteenth  of  an  inch,  gradually  increasing  this 
distance  as  the  carbons  heat  up  until  the  proper  length  of 
arc  to  supply  maximum  screen  illumination  is  reached, 
whereupon  the  voltmeter  should  register  about  55  volts  at 
the  arc  and  the  ammeter  about  35  amperes,  where  the  35 
ampere  set  is  used,  or  55  volts  at  the  arc  and  50  amperes 
if  it  is  a  50  ampere  outfit. 

Caution. — The  closing  of  the  carbons  short  circuits  the 
generator,  and,  of  course,  instantly  creates  an  overload.  The 
generator  is  wound  to  protect  itself  against  this  very  thing,  and 
unless  the  carbons  are  instantly  separated  the  generator  will 
lose  its  voltage-  This  does  no  harm  to  the  machine,  but  it 
will  be  necessary  to  separate  the  carbons  for  perhaps  ten  sec- 
onds until  the  voltage  again  reaches  normal,  zvhereupon  the  arc 
may  be  struck  in  the  usual  manner. 

As  the  machine  warms  up  it  may  be  necessary  to  move  the 
handle  of  the  rheostat  one  or  two  buttons  away  from  the 
mark,  to  the  left,  in  order  to  maintain  the  desired  voltage  and 
amperage  at  the  arc. 

Reversing  Connections.— Provided  the  circuits  have  been 
connected  as  shown  in  the  diagram  the  polarity  will  be  as 
indicated,  and  the  upper  carbon  of  the  lamp  will  be  positive. 
Should  an  error  be  made  in  connections,  and  either  or  both 
the  voltmeter  and  ammeter  read  backward,  the  trouble  must 
be  corrected.  Examine  all  diagrams  and  see  that  all  con- 
nections are  made  in  accordance  therewith,  particularly  that 
the  motor  terminals  are  connected  to  the  proper  side  of  the 
line.  Do  not  attempt  to  correct  trouble  by  reversing  the 
terminals  at  the  generator.  The  machines  are  all  carefully 
checked  up  complete  with  their  equipment  when  tested,  and 


388 


MOTION    PICTURE    HANDBOOK 


the  motor  must,  therefore,  be  connected  to  the  proper  side 
of  the  line  in  order  to  bring  the  polarity  of  the  voltmeter 
and  ammeter  of  the  projection  lamp  right. 


One-Lamp  Outfit. 
Plate  6. 


Two-Lamp  Outfit. 
Plate  7. 


Internal  Connection  Diagram  A.  C.  to  D.  C.  Compensarcs. 
Figure  186. 

The  operation  of  the  two-lamp-alternately  equipment  is 
the  same  as  for  the  two-lamp-alternately  A.  C.  to  D.  C. 
compensarc. 

Starting  A.  C.  to  D.  C.  Compensarcs.— In  starting  A.  C. 
to  D.  C.  Compensarcs,  see  that  the  projection  lamp  switch 
is  open.  If  the  motor  is  single  phase,  close  the  main  line 
switch  and  move  the  starting  box  arm  from  "off"  position  to 
the  split  segment,  which  will  put  into  action  the  number  of 
starting  coils  necessary  to  cause  the  armature  to  rotate. 
When  the  armature  has  attained  nearly  full  speed,  the  arm  of 
the  starting  box  should  be  moved  quickly  over  to  the  last 
segment  where  it  is  held  by  a  latch  controlled  by  a 
relay  magnet.  Should  the  voltage  at  any  time  fail,  the  relay 
magnet  will  release  the  latch,  allowing  the  starting  arm  to 
automatically  return  to  the  "off"  position,  thus  protecting 
the  motor  armature  from  damage  in  case  the  voltage  comes 
on  again. 


FOR    MANAGERS   AND    OPERATORS  389 

The  two  and  three  phase  outfits  do  not  require  starting 
boxes,  but  should  be  equipped  with  double-throw  starting 
switches  which  have  only  one  side  fused.  When  starting  up 
the  switch  should  first  be  closed  to  the  unfused  side.  When 
the  speed  of  the  armature  reaches  normal  the  switch  should 
be  quickly  thrown  over  to  the  running  (fused)  side.  When  the 


Plate  10,  Figure  187. 

speed  of  the  motor  reaches  normal,  the  starting  box  handle 
or  the  double-throw  switch  in  running  position,  and  the 
rheostat  handle  set  as  indicated  by  the  white  arrow,  the 
projection  machine  switch  may  be  closed  and  the  arc  struck 
as  described  under  "Starting  D.  C.  Compensarcs." 

The  coupling  between  the  motor  and  generator  is  marked 
to  show  the  direction  in  which  the  armature  should  revolve. 
It  should  run  clockwise  as  one  faces  the  generator  commu- 
tator. The  direction  of  rotation  of  two-phase  induction 
motors  may  be  reversed  by  interchanging  the  two  stator 
leads  of  the  same  phase.  In  the  case  of  single  or  three  phase 
motors  it  is  only  necessary  to  interchange  any  two  leads. 

Operating  Directions  for  Two-Lamp  Outfits,  both  D.  C.  to 
D.  C.  and  A.  C.  to  D.  C. — The  motor  of  the  two  lamp 
outfits  is  started  the  same  as  the  regular  single-lamp  outfits, 
directions  for  which  have  already  been  given. 

Have  change-over  switch  (by  change-o(ver  switch  the 
single  pole  double  contact  switch  is  meant)  on  the  panel 
closed,  and  start  the  first  lamp  by  closing  the  switch  and 
striking  the  arc  in  the  usual  manner.  When  it  is  desired 
to  change  from  one  lamp  to  the  other,  open  change-over 
switch  while  the  first  lamp  is  still  burning,  then  close  the 


390  MOTION    PICTURE    HANDBOOK 

projection  machine  switch  of  the  second  lamp  and  strike 
its  arc.  Open  the  projection  machine  switch  at  the  lamp 
which  is  to  be  cut  out,  and  then  close  the  change-over 
switch.  By  tracing  the  connections  in  Fig.  182  and  Plate 
9  it  will  be  seen  that  when  the  change-over  switch  is  opened 
the  current  must  flow  to  the  lamp  which  is  burning,  and 
must  pass  through  grid  resistance,  which  has  the  effect 
of  steadying  the  arc  and  preventing  it  from  going  out  at 
the  instant  the  arc  is  struck  at  the  second  lamp.  It  is 
therefore  possible  to  strike  the  second  arc  and  burn  the 
crater  into  proper  shape  while  the  end  of  the  first  reel  is 
still  being  projected,  and  to  accomplish  the  effect  of  dis- 
solving one  picture  into  the  next.  The  steadying  resistance 
is  only  in  circuit  when  both  lamps  are  burning,  and  care 
must  be  taken  that  the  change-over  switch  is  kept  closed 
when  only  one  lamp  is  burning.  If,  for  any  reason,  an 
increase  in  current  is  needed  at  the  arc,  or  it  is  necessary 
to  heat  up  the  carbons  very  quickly,  the  change-over  switch 
may  be  opened  on  one  lamp  for  a  few  minutes,  thus  in- 
creasing the  current  in  the  arc  without  disturbing  the  field 
rheostat  setting. 

Caution.. — Keep  the  first  arc  rather  short  at  the  instant  the 
second  arc  is  struck. 

If  this  is  done  neither  arc  will  go  out,  or  even  flutter 
during  the  period  of  lighting  the  other  arc.  The  ability  to 
handle  both  arcs  perfectly  and  change  over  without  a 
flicker  in  the  picture  is  soon  acquired,  and  if  the  second  arc 
is  started  long  enough  ahead  to  be  perfectly  steady  there 
is  no  difficulty  in  dissolving  one  picture  into  the  next 
sucessfully. 

Caution. — Care  must  be  taken  that  the  two  lamps  are  not 
burned  longer  than  is  really  necessary,  since  the  compensarc  is 
not  intended  to  carry  both  lamps  continuously,  neither  has  it 
the  capacity  to  do  so. 

With  one  lamp  burning  the  ammeter  will  show  from  35 
to  50  amperes,  and  the  voltmeter  about  55  volts;  when  both 
lamps  are  burning  the  ammeter  will  show  approximately 
70  to  100  amperes  and  the  voltmeter  70  to  75  volts,  the 
voltage  being  automatically  increased  to  compensate  for  the 
drop  in  the  grid  resistance.  The  voltmeter,  as  shown  in 
the  diagram,  Plate  4,  is  connected  across  machine  terminals 
1  and  3  and  indicates  the  machine  voltage,  which  is  the 
same  as  the  arc  voltage  when  the  change-over  switch  is 
closed. 


FOR    MANAGERS    AND    OPERATORS  391 

Care  of  Machine. — Cleanliness.  See  General  Instruction 
No.  5. 

Oil. — See  General  Instruction  No.  3;  also,  in  addition, 
immediately  after  starting  a  new  outfit  raise  the  bearing 
caps  and  see  that  the  oil  rings  are  revolving  freely  and 
carrying  oil  up  to  the  top  of  the  shaft.  Keep  the  oil  to 
the  proper  level  in  the  well,  which  is  nearly  to  the 
lip  of  the  overflow  oil  gauge.  The  oil  wells  should  be 
cleaned  out  occasionally  and  new  oil  supplied.  They  should 
invariably  be  filled  through  the  side  filling  hole  and  not 
through  the  top  of  the  bearing.  If  filled  through  the  top 
the  oil  is  likely  to  run  out  through  the  ends  of  bearings, 
get  into  the  windings  and  do  damage. 

Bearings. — As  soon  as  the  bearing  linings  become  worn 
so  that  the  armature  is  in  danger  of  rubbing  against  the 
stator,  a  new  set  of  bearing  linings  must  be  inserted.  To 
remove  the  bearings  first  take  out  the  set  screws  in  the 
bearing-housing.  Having  done  this  lift  the  oil  rings  up  so 
that  they  clear  the  bearing  lining;  to  lift  rings  use  a  wire 
with  a  hook  bent  on  one  end  and  raise  rings  with  wire 
through  the  bearing  cover  and  drive  out  the  bearing  linings 
with  a  wooden  block  of  the  same  diameter  as  the  bearings 
themselves.  The  bearings  are  so  made  that  they  fit  the  hole 
in  the  housing  snugly  enough  to  require  light  driving  to 
seat  them,  and  they  must  be  handled  carefully  and  intelli- 
gently. When  duplicate  bearings  are  supplied  for  the  alter- 
nating current  motor  the  set  screw  depression  is  already  in 
the  bearing,  but  the  D.  C.  motor  generator  bearings,  which 
regulate  the  end  play,  are  supplied  without  the  spot  for 
the  end  of  the  set  screw  and  they  must  be  spotted  before 
being  put  into  place.  Use  a  three-sixteenth  inch  drill  and 
drill  a  spot  for  the  tip  of  the  set  screw  the  same  distance  from 
the  end  of  the  bearing  as  the  one  being  replaced. 

Care  of  Commutator  and  Brushes. — See  "General  Instruc- 
tion," No.  4,  and  in  addition,  to  secure  proper  commutation 
and  proper  operation  the  brushes  must  occupy  the  correct 
position  on  the  commutator.  The  proper  position  of  the 
brush  has  been  determined  at  the  factory,  and  is  indicated 
by  chisel  marks,  filled  with  white  lead,  on  the  brush  yoke 
and  frame. 

//  is  very  important  that  these  marks  be  in  line  with  each 
other. 

Should  the  brush  holders  become  loosened  or  moved  in  any 


392 


MOTION    PICTURE    HANDBOOK 


Commutator 


Direction  of 
Rotation 
Plate  11,  Figure  188. 


way  they  must  be  carefully  reset  so  that  they  may  make 
proper  angle  with  the  commutator,  as  shown  in  Plate  11. 
They  must  also  be  so  placed  around  the  commutator  that 
the  distance  from  tip  to  tip  of  the  brushes  is  exactly  the 
same  when  measured  both  ways  around  the  commutator. 

See  Fig.  180,  Page  375.  Care 
should  be  taken  that  the  brush 
holder  be  securely  fastened  at  an 
even  height,  one-sixteenth  of  an 
inch  above  the  commutator.  It  is 
recommended  that  an  extra  set 
of  brushes  be  kept  on  hand. 
Brushes  may  be  worn  down  to 
approximately  three-quarters  of 
an  inch  in  length.  Only  brushes 
of  the  proper  grade  will  give 
satisfactory  results,  therefore  only 
the  brush  furnished  with  the 
machine  or  others  exactly  the 
same  grade  should  be  used. 

Loose  Connections. — See  "Gen- 
eral  Instruction"   No.  6. 
Loose  Connections. — See  "General  Instruction"  No.  6. 
Trouble. — All   compensarcs  are  carefully  inspected  at  the 
factory  and  tested  on  a  projection  arc  lamp  under  actual  oper- 
ating conditions,  as  nearly  as  they  can  be  secured  in  a  factory, 
therefore  when  the  machine   is   received  by  the  operator  it 
is  ready  to  set  up  and  run.     If  trouble  is  experienced  do  not 
blame  the  machine  until  you  are  certain  it  does  not  lie  in 
some  part  of  the  equipment  or  in  some  local  condition. 

Ordering  Repairs. — If  it  is  at  any  time  necessary  to  order 
repair  parts,  such  as  new  brushes,  new  bearings,  etc.,  bear 
carefully  in  mind  the  fact  that  the  serial  number  and  name  plate 
readings  of  the  machine  must  be  placed  on  the  order. 

D.  C.  Compensarcs. — Machine  will  not  start:  If  the  ma- 
chine does  not  start  first  examine  the  fuses  and  make  sure 
that  the  power  is  on  at  the  switch  terminals.  Then  trace 
and  inspect  the  connections  from  the  switch  through  the 
starting  box,  armature,  brushes,  field  and  back  to  the  switch, 
and  an  opening  in  the  circuit  will  probably  be  found. 

Fuses  Blow:  If  the  fuses  blow  make  sure  they  are  of 
proper  size  for  the  amperage  used,  and  not  loose  in  their 
contacts.  Examine  the  starting  box  for  grounded  or  short 
circuited  resistance  coils.  Look  inside  the  machine  and  see 
that  the  connections  are  not  touching  inside  where  they  are 


FOR   MANAGERS   AND    OPERATORS  393 

not  easily  seen.  See  that  the  brush  yoke  and  housing  marks 
agree,  to  insure  that  the  brushes  are  set  in  same  position  as 
when  adjusted  at  the  factory.  Look  all  around  the  commu- 
tator at  the  connections  between  the  armature  windings  and 
the  commutator  bars.  Such  minute  inspection  should  locate 
the  trouble. 

A.  C.  to  D.  C.  Compensates.— Machine  does  not  start:  If 
the  machine  does  not  start  when  the  switch  is  closed,  first 
examine  the  fuses  and  make  sure  the  current  is  on  at  the 
switch  terminals.  It  sometimes  happens  that  a  single  fuse 
has  blown  on  a  three-phase  three-wire  outfit,  in  which  case 
the  compensarc  will  run  as  a  single-phase  machine,  but  if 
stopped  will  not  start  again  until  the  blown  fuse  has  been 
replaced  if  a  single  throw  switch  be  used.  However,  if  a 
double  throw  starting  switch  be  used  the  compensarc  will  be 
started  up  on  the  unfused  side.  Therefore,  the  missing  fuse 
must  be  detected  by  the  operation  of  the  machine  while 
running.  If  a  fuse  is  missing  it  can  usually  be  detected  by 
the  unusual  noise  made  by  the  machine  while  running,  by 
the  motor  end  heating  excessively,  and  more  particularly 
by  change  in  speed  with  change  in  load,  and  general  un- 
steadiness of  the  arc.  If  a  fuse  be  blown  it  should  be  re- 
placed immediately,  else  it  may  cause  the  burning  out  of 
the  motor. 

D.  C.  and  A.  C.  to  D.  C.  Compensates. — Sparking  at  the 
brushes:  When  a  vicious  sparking  develops  under  the 
brushes  of  the  compensarc  it  is  an  indication  that  something 
is  radically  wrong.  The  most  usual  causes  are  dealt  with 
fully  under  General  Instruction  No.  8,  Page  372.  In  addi- 
tion it  may  be  noted,  however,  that  in  removing  the  brushes 
from  the  boxes  for  cleaning,  which  should  be  done  once  a 
week,  do  not  take  the  pig  tails  loose  front  the  brush  holders, 
and  be  sure  to  place  the  brushes  back  in  the  boxes  in  their 
original  position,  for  if  they  are  turned  around  they  will 
not  fit  the  commutator  surface.  The  brushes  should  have  a 
smooth,  unscratched  surface,  free  from  any  copper  deposit. 

Open  or  Short  Circuit  in  Armature:  This  trouble  will  most 
often  occur  where  the  armature  winding  is  connected  to  the 
commutator,  and  results  generally  from  a  bruise  in  handling, 
from  some  foreign  body  getting  caught  in  the  armature,  or 
from  a  chip  caught  when  the  commutator  is  being  turned 
or  repaired.  If  an  open  circuit  the  trouble  is  very  apparent, 
since  the  long  heavy  spark  accompanying  it  generally  eats 
away  the  mica  between  the  segments  on  each  side  of  the 
break,  thus  indicating  its  location.  A  short  circuit  in  the 


394  MOTION    PICTURE    HANDBOOK 

armature  will  show  at  once  by  the  excessive  heating,  and 
perhaps  smoking  of  .the  coil  or  coils  short  circuited  and  if 
the  machine  is  continued  in  operation  it  will  be  burned  out. 
Where  trouble  of  this  kind  is  suspected  the  necessity  of 
prompt  attention  by  an  electrician  is  obvious. 

Overload:  If  considerably  more  current  is  being  taken  by 
the  lamp  than  the  machine  is  designed  for,  sparking  may 
result.  See  that  the  machine  is  not  excessively  overloaded. 

Brushes  in  wrong  position:  If  the  brushes  are  left  in  the 
same  position  as  when  the  machine  is  received,  trouble  will 
not  occur  from  this  cause.  If  brushes  are  ever  moved  or 
changed,  see  that  they  are  put  back  where  they  belong, 
and  that  marks  on  brush  yoke  and  bearing  housing  agree. 

Machine  makes  excessive  noise:  This  is  most  often  due 
to  a  weak  floor,  or  to  the  machine  not  setting  firm  and 
level.  If  the  noise  seems  to  be  in  the  machine  itself,  and 
nothing  can  be  observed  out  of  place,  send  for  an  electri- 
cian, as  the  trouble  may  be  serious. 

Bearings  run  hot:     See  General  Instruction  No.  10. 

TO  SECURE  THE  BEST  RESULTS 

(1)  Keep  the  machine  clean. 

(2)  Keep    the    oil    wells    full    (not    overflowing)    of    good 
clean   lubricating   oil. 

(3)  Keep  the  commutator  and  brushes  free  from  gum  and 
grease. 

(4)  Keep   contacts  clean  and  tight. 

(5)  Keep  lamp  and  wiring  free  from  grounds. 

(6)  Keep  the  current  at  the  arc  within  the  rating  of  the 
machine. 

When  repair  parts  are  needed  it  is  poor  economy  to  try  to 
get  along  without  them.  Brushes  and  bearings  for  these 
machines  can  be  shipped  on  short  notice  and  will  always 
be  of  correct  size  and  quality.  In  ordering  from  the  manu- 
facturer simply  give  the  nameplate  marking,  serial  number, 
etc.,  and  no  difficulty  will  be  experienced  in  promptly  secur- 
ing the  desired  parts. 


FOR  MANAGERS  AND  OPERATORS 


395 


The  Wotton  Vertical  Rexolux 

THE  Wotton   Rexolux  is   a  new,  vertical   motor   generator 
set,   manufactured  by  the   Electric  Products  Company, 
Cleveland,  Ohio,  designed  particularly  for  motion  pic- 
ture work.     The  word  "Rexolux"  is  a  trade  name  meaning 
King  of  Light. 

This  machine  is  a  vertical  motor  generator  set,  converting 
alternating    current    of    standard    line    voltage    into    direct 

current    at    arc    voltage.      The 

machine  is  built  vertical  with 
a  view  of  allowing  its  installa- 
tion in  the  operating  room,  even 
when  space  is  limited,  thus 
placing  the  machine  directly 
under  the  eye  of  the  operator; 
also,  the  vertical  design  permits 
of  a  rugged  form  of  construc- 
tion which  tends  to  reduce  vi- 
bration and  noise  to  a  minimum; 
also  it  makes  the  machine  very 
accessible  and  easy  to  assemble 
and  disassemble. 

The  Rexolux  is  built  in  three 
sizes,  viz:  a  machine  designed 
to  operate  a  single  projection- 
arc  lamp;  a  machine  to  operate 
two  lamps  alternately,  and  one 
to  operate  two  lamps  continu- 
ously. Where  two  lamps  are 
operated  continuously  only  the 
70  ampere  machine  is  available. 

Tihe  50  ampere  machine,  of 
either  the  M,  MA,  or  MMA  type 
(the  meaning  of  these  different 
types  will  be  explained  later 
on),  occupies  a  floor  space  17 
by  20  inches,  and  has  a  vertical 
height  of  34  inches  to  the  top 
of  cap  14,  P.  1.  The  switch- 


Plate  1,  Figure  189. 


board,  supported  by  angle  irons,  is  immediately  over  the 
machine,  so  that  the  entire  space  required  for  the  50  ampere 
equipment  is  17  by  20  inches  on  the  floor,  by  5  feet  in  vertical 
height.  The  35  ampere  machine  is  3  inches  less  and  the  70 


396 


MOTION    PICTURE   HANDBOOK 


ampere  is  3  inches  greater  in  height,  but  the*  floor  space 
required  is  practically  the  same  for  all  the  types. 

In  referring  to  the  ampere  capacity  of  the  above  machines, 
the  ratings  are  based  on  continuous  operation.  The  35  am- 
pere machine  will  carry  SO  amperes,  the  50  ampere  machine 
80  amperes  and  the  70  ampere  140  amperes  for  short  periods 
of  time,  meaning  by  this  that  these  machines  will  carry  full 
load  continuously,  and  stand  the  overload  named  for  short 
periods,  say  not  exceeding  two  or  three  minutes. 

These  machines  are  built  for  all  standard  voltages  and 
frequencies,  viz:  110,  220,  440  and  550  volts;  25,  30,  40,  50  and 
60  cycles,  single,  two  and  three  phase. 

Construction. — Referring  to  Plate  2,  Fig.  190,  it  will  be 
seen  that  the  machine  consists  of  four  main  castings,  viz: 
base  casting  20,  which  rests  directly  on  the  floor,  and  con- 


Plate  2,  Figure  190. 

Iff  - 
tains  in  its  center  the  cup  or  depression  carrying  ball  race  6, 

which  supports  the  entire  armature;  casting  18,  which  rests 
on  base  20  and  forms  a  housing  for  the  alternating!  cur- 
rent driving  motor,  the  detailed  construction  of  the  wind- 
ings of  which  are  plainly  seen  at  19,  Plate  2;  main  upper 
casting  7,  which  supports  the  pole  pieces  of  the  D.  C.  gen- 
erator, and  upper  yoke  casting  11,  carrying  grating  23,  the 
upper  armature  bearing,  and  cap  14,  Plate  1;  main  upper 
casting  7,  Plate  2,  and  yoke  castings  11,  Plate  2,  are  held 
together  by  bolt  27,  Plate  2,  dividing  at  the  dotted  line. 
The  armature  stands  vertical  (on  end),  with  the  rotor  of 


FOR    MANAGERS    AND    OPERATORS 


397 


the  alternating  motor,  4,  Plate  2,  below,  fan  5  above  rotor 
4,  and  armature  1  with  commutator  2,  above  the  fan,  the 
upper  end  being  supported  laterally  by  a  ball  bearing,  con- 
struction of  which  is  shown  in  detail  in  Plate  3,  Brush 
holders  and  brushes  17  are  shown  in  Plate  2. 


Plate  3;  Figure  191. 

The  details  of  upper  bearing  3,  Plate  2,  are  shown  in  Plate 
3,  in  which  4  and  5  are,,  respectively,  an  exterior  and  interior 
ball  race,  separated  by  steel  balls  6,  part  5,  the  interior  race 
being  clamped  rigidly  to  shaft  9,  by  means  of  nut  2.  Part 
4  is  stationary  and  sets  in  a  recess  in  the  main  frame  casting, 
the  whole  being  covered  by  cap  1.  Part  7  consists  of  a 
casting  which  is  clamped  between  interior  ball  race  5,  and  the 
shoulder,  pf  shaft  9,  so  that  it  must  revolve  with  the  shaft 
at  armature  speed.  This  part  (7)  extends  down1  into  oil 
well  10.  The  oiling  action  is  as  follows:  Oil  well  10  is  filled 
with  oil  up  tp  approximately  one-quarter  inch  of  the  top 
of  the  passage  containing  plug  13.  Part  7  revolves  at  high 
speed,  and,  by  the  centrifugal  action  thus  created  the  oil  is 
forced  up  through  passage  3-3,  whence  by  gravity  it  returns 
again  to  the  well  through  the  bearing,  thus  flooding  balls 
6  with  a  continuous  stream  of  oil. 

Thirteen,  Plates  !-••  2  and  3,  is  a  plug  closing  the  passage 


398  MOTION    PICTURE    HANDBOOK 

through  which  oil  well  10  is  filled.  It  is  essential  that  this  plug 
be  in  place  and  screwed  tightly  home,  else  the  centrifugal  action 
before  named  will  force  the  oil  out  and  empty  the  zvell.  Plug 
12,  Plates  1,  2  and  3;  is  for  the  purpose  of  draining  oil  well 
10,  and  this  should  be  done  at  regular  intervals  every  thirty  days. 
After  draining  the  oil  well,  insert  plug  12  and  fill  the  well 
with  kerosense,  start  the  machine  and  let  it  run  for  say  two 
minutes,  after  which  drain  all  the  kerosense  out,  replace 
plug  12  and  fill  the  well  up  to  within  one-quarter  inch  of  the 
top  of  the  passage  stopped  by  plug  13. 

As  the  quality  of  oil  to  be  used,  see  General  Instruction 
No.  3,  but: 

Caution. — Never,  under  any  circumstances,  use  the  much 
advertised  patent  oils,  as  they  almost  without  exception  are 
worthless  for  the  lubrication  of  heavy  or  high  speed  machinery. 
The  use  of  such  oils  will  invalidate  the  manufacturer's  guarantee. 

On  the  other,  or  lower  end  of  the  armature  shaft,  is  ball 
bearing  6,  Plate  2,  lubrication  for  which  is  furnished  by  grease 
cup  21,  Plates  1  and  2.  This  grease  cup  should  be  kept  filled 
with  Alco  Grease. 

Caution. — It  is  important  that  either  Alco  Grease  or  a  high 
grade  vaseline  be  used,  because  of  the  fact  that  if  a  grease 
containing  any  acid  is  used  in  cup  21,  the  acid  will  attack  the 
steel  balls,  and  in  course  of  time  destroy  their  accuracy,  thus 
compelling  an  unnecessary  and  somewhat  expensive  renewal  of 
the  bearing. 

Armature. — The  armature  or  revolving  member  of  the  ma- 
chine is  completely  assembled  into  one  solid  part,  1  to  6, 
Plate  2,  in  which  3  is  the  upper  and  6  the  lower  bearing. 
The  alternating  current  rotor,  or  revolving  member,  4,  is 
built  up  of  reannealed  electrical  sheet  steel,  properly  punched  and 
assembled  on  armature  shaft  9.  The  rotor  bars  are  driven 
through  the  slots  a  tight  fit,  the  ends  electrically  welded 
together  into  a  solid  mass  of  pure  copper,  which  insures 
perfect  contact,  low  resistance  and  a  uniform  torque,  or 
pulling  force.  Directly  above  the  rotor  is  fan  5,  Plate  2, 
made  of  sheet  steel  blades  and  a  solid  ring,  the  blades 
riveted  and  welded  together,  and  finally  attached  to  shaft  9 
by  means  of  two  heavy  set  screws.  This  fan  produces  a 
suction  through  the  ventilating  openings  in  castings  18  and 
20,  drawing  cold  air  over  the  windings  of  the  A.  C.  motor. 
This  air  is  then  forced  up  over  this  D.  C.  armature,  and  out 
through  openings  23,  Plate  1. 

Part  1,  Plate  2,  is  the  D.  C.  armature,  which  is  mounted 
directly  above  fan  5.  Armature  coils  are  fixed  in  place  with 


FOR    MANAGERS   AND    OPERATORS 


399 


retaining  band  wires  where  the  connections  are  made  to  com- 
mutator 2,  Plate  2.  The  commutator  is  made  up  of  hard  drawn 
copper  segments,  insulated  with  mica,  and  held  in  place  with  steel 
rings  clamped  with  four  bolts.  The  D.  C.  generator  is  of  the 
four-pole  type,  and  is  provided  with  commutating  or  inner  poles. 

Brushes.— The  setting 
of  the  brushes  is  shown 
in  Plate  4.  There  are 
four  brush  studs,  17, 
Plate  1,  and  two 
brushes  to  a  stud.  These 
brushes  are  attached  to 
the  holders  by  copper 
"pigtails."  Particular 
care  should  be  exercised 
to  see  that  the  screw 
holding  the  pigtail  to 
the  brush  holder  is  kept 
set  up  tight,  because 
unless  the  pigtail  makes 
good  contact  with  the 
holder,  the  tension 
spring  will  be  com-  Plate  4,  Figure  192. 

pelled  to  carry  current, 

which  would  probably  heat  the  brush  spring  and  destroy 
its  temper. 

With  regard  to  the  amount  of  tension  the  brushes  should 
have  see  General  Instruction  No.  8. 

The  brushes  are  held  in  place  by  a  curved  arm  pass- 
ing around  the  holder,  ending  in  a  tension  ringer  fitting  on 
the  top  of  the  brush.  The  brushes  are  held  to  the  commu- 
tator against  the  direction  of  rotation.  The  amount  of  tension 
can  be  adjusted  by  the  spring  and  ratchet  on  the  side  of  the 
brush  holder. 

Care  of  Commutator. — With  regard  to  the  care  of  the 
commutator,  see  General  Instruction  No.  8, 

The  A.  C.  driving  motor  is  the  induction  type,  and  is  built 
either  for  single,  two  or  three  phase  current,  but  the  same 
machine  will  not  operate  on  different  phases.  All  standard 
machines  are  built  to  operate  on  both  110  and  220  volts. 

Installation. — See  General  Instruction  Nos.  1  and  2. 

The  Rexolux  is  so  built  that  it  may  be  readily  disassembled, 
since  owing  to  its  weight  it  would  in  many  cases  be  difficult 
to  hoist  it  in  place  in  an  operating  room  as  a  unit.  In  order 
to  disassemble  the  machine,  proceed  as  follows: 


400  MOTION    PICTURE    HANDBOOK 

First,  open  gratings  23,  Plate  1,  and  remove  the  commu- 
tator brushes  from  their  holders,  allowing  them  to  hang  by 
their  pig-tails  so  that  you  can  make  no  mistake  in  getting  them 
back  into  their  proper  holder.  Remove  screws  26,  holding 
cap  14,  Plate  1.  Remove  nut  2,  Plate  3.  Remove  nuts  24, 
Plate  1  (four  of  them),  holding  main  upper  casting  7,  and 
main  lower  casting  18  together.  Screw  the  eye-bolts  pro- 
vided into  holes  in  main  upper  casting  7.  (These  holes  were 
not  in  the  first  machines  put  out).  Thrust  pieces  of  gas 
pipe  or  steel  bars  through  the  eye-bolts  and  lift  main  casting 
7  straight  up  and  off,  laying  it  to  one  side,  but  right  side 
up  so  that  oil  will  not  run  out  of  oil  well  10,  Plate  3.  Next 
carefully  lift  out  the  armature,  first,  however,  having  pro- 
vided two  blocks  or  chairs,  and  lay  the  same  down  flatways  on 
these  blocks  or  chairs,  so  that  the  weight  is  entirely  supported 
by  the  shaft. 

It  is  very  important  that  you  do  not  lay  the  armature 
down  so  that  it  rests  on  the  side  of  the  alternating  current 
rotor  4,  fan  5,  or  direct  current  armature  1,  or  commutator 
2,  since  any  injury  to  these  would  be  a  very  serious  matter 
indeed.  Handle  the  armature  carefully  and  use  a  little  horse 
sense,  if  you  wish  to  avoid  trouble.  The  machine  may  now 
be  hoisted  or  carried  into  the  operating  room,  where  its 
reassembling  will  merely  be  a  reversal  of  the  process  of 
disassembling.  First  carefully  lower  the  armature  into  place, 
being  careful  that  alternating  current  rotor  4,  Plate  2,  be  on 
the  lower  end.  Next  replace  casting  7,  and  tighten  up  nuts 
24,  Plate  1,  tight.  Replace  top  ball  races  and  nut  2,  Plate  3, 
tightening  nut  2  down  as  tight  as  you  can  get  it.  Replace 
cap  14  nd  screws  26.  Rotate  the  armature  by  hand  to  see 
that  it  turns  freely,  after  which  replace  the  brushes  in  their 
holders,  put  gratings  25,  Plate  1,  back  into  place,  and  the 
job  is  done. 

Be  sure  and  wipe  the  inside  of  the  top  casting,  clean,  since 
if  any  oil  should  get  on  it,  it  would  collect  the  copper  dust 
from  the  commutator  and  might  cause  a  ground  on  the  brush 
yoke.  See  that  the  casting  and  brush  yoke  are  thoroughly 
cleaned  of  all  oil  and  dust  before  it  is  put  back  in  place. 
It  would  be  preferable  to  wash  them  with  a  cloth  dipped  in 
gasoline,  wiping  with  a  clean,  dry  cloth  afterward. 

Bolts  29,  Plate  1,  hold  pole  piece  8,  Plate  2,  which  carries 
coil  9,  Plate  2,  in  place,  and  should  not  be  removed  under 
any  circumstances,  unless  the  coil  be  damaged  and  require 
rewinding.  There  are  four  of  these  pole  pieces  and  eight 
bolts,  two  bolts  per  pole  piece.  Bolts  30,  Plate  1,  hold 


FOR   MANAGERS   AND   OPERATORS 


401 


Direct/ or?  of         L.t 
ffofafion    : 


/7/^>/?/  ft  and  /ook  - 
//7g  down  or?  ton . 


Plate  5,  Figure  193. 


402  MOTION    PICTURE    HANDBOOK 

inner  poles  10,  Plate  2,  in  place,  and  should  not  be  lemoved 
under  any  circumstances  unless  the  coil  is  burned  out  and 
requires  rewinding. 

Remember  the  switchboard  sets  directly  over  the  machine, 
as  shown  in  Plate  1.  With  each  machine  there  is  furnished 
four  cork  pads,  2  inches  square  by  1  inch  thick,  which  are 
to  be  placed  under  the  feet  of  the  machine,  where  they  act 
as  a  cushion,  absorbing  noise  and  vibration.  It  is  not 
necessary  nor  do  we  recommend  screwing  the  machine  to 
the  floor  with  lag  bolts.  Its  weight  is  sufficient  to  hold  it  in 
place. 

ELECTRICAL   CONNECTIONS— TYPE   MA    SINGLE 
ARC  REXOLUX 

In  Plate  5,  lines  G-G  show  the  direct  current  circuits. 
The  current  from  the  positive  generator  brush  passes  out  at 
+  G,  thence  over  the  evenly  dotted  line  to  switch  B  (G, 
Plate  1),  which  when  closed,  connects,  after  passing  through 
the  ammeter,  with  the  positive  carbons  of  the  arc  lamp. 
From  the  negative  brush  of  the  generator  the  current  passes 
through  the  various  interpole  coils  in  series,  then  out  at  —  G, 
thence  similarly  up  to  the  negative  side  of  switch  B,  and 
thence  to  the  arc.  In  order  to  obtain  the  necessary  field 
regulation,  the  extra  lead  from  the  shunt  field  is  brought 
through  the  frame  at  F,  Plate  5,  and  thence  up  to  the  field 
regulating  resistance.  The  voltmeter  is  connected  across 
the  terminals  of  the  arc  at  the  right  hand  side  of  switch  B. 
This  completes  the  direct  current  connection  for  the  type 
MA  single  arc  Rexolux. 

Were  it  not  necessary  to  obtain  a  self-starting  motor,  in 
single  phase  machines,  it  would  then  require  but  one  set  of 
windings.  In  order,  however,  to  obtain  the  necessary  start- 
ing torque,  a  second  set  of  wire  coils  is  superimposed  upon 
the  main  power  coils.  This  set  of  starting  coils  is  thrown 
out  of  phase  with  the  power  coils  by  inserting  in  series 
therewith  a  starting  resistance  and  reactance,  shown  opposite 
starting  switch  A,  Plate  5.  The  main  power  coils  terminate 
in  the  frame  at  "Ml"  and  "M2,"  Plate  5,  and  the  terminals 
of  the  extra  starting  coil  at  T,  the  other  end  of  which  is 
connected  inside  of  the  machine  to  the  main  power  coils. 
The  lines  designated  by  a  dash  and  a  dot  constitute  the 
alternating  current  wiring  of  the  system. 

Where  two  or  three  phase  current  is  supplied  it  is  not 
necessary  to  use  the  extra  starting  coils,  or  the  starting 


FOR    MANAGERS    AND    OPERATORS 


403 


I 


-p^.     i     ^  SS- 

L._.-L  \jL/r?e 
£jw[ * 1 

flBlll    P         p»-^^ 

M— -n-- 


en 


1    ? 


i 


ipuii 

' • 


404  MOTION    PICTURE   HANDBOOK 

resistance  or  the  reactance.     In  this  case  the  wiring  incident 
to  the  starting  features  of  the  single  phase  motor  is  omitted. 

ELECTRICAL  CONNECTIONS— TYPE  MMA— TWO 
ARC  REXOLUX 

An  examination  of  Plate  6  will  show  that  the  motor  start- 
ing and  control  is  identical  with  that  shown  in  Plate  5, 
therefore  what  has  already  been  said  of  Plate  5  applies.  By 
reason  of  the  fact  that  a  shunt  wound  generator  drops  its 
voltage  when  overloaded,  thus  automatically  protecting  it- 
self when  the  carbons  are  brought  together  for  the  purpose 
of  striking  the  arc,  the  shunt  wound  generator  is  ideal.  Since, 
however,  upon  short  circuiting  the  carbons  the  field  of  the 
machine .  is  entirely  destroyed,  it  is  impossible  to  run  a 
shunt  wound  machine  and  keep  one  arc  burning  while  the 
other  is  struck.  During  the  period  of  changing  from  one 
projector  to  another  to  dissolve  one  picture  into  the  next, 
it  is  necessary  to  operate  the  generator  temporarily  during  the 
changeover  interval,  as  a  compound  wound  machine.  The 
regulator  shown  above  the  center  of  the  board  accomplishes 
the  changeover  from  shunt  to  compound  wound  during  the 
time  both  arcs  are  burning,  and  then  back  to  the  shunt 
again  when  ready  to  extinguish  one  of  the  arcs.  Regulator 
C  accomplishes  the  whole  changeover  process  without 
touching  anything  else. 

As  in  the  previous  description  "+  G"  and  " —  G"  are  the 
main  generator  leads  as  they  pass  from  positive  and  negative 
brushes  respectively  to  the  generator  frame.  In  the  two-arc  ma- 
chine, however,  the  current  passing  from  the  negative  brush  first 
passes  through  the  system  of  interpoles,  thence  through  a 
separate  series  winding,  wound  on  the  main  generator  field 
poles.  A  tap  is  taken  between  the  end  of  the  interpole 
system  and  the  beginning  of  the  series  winding  and  carried 
out  through  the  frame  at  "S."  The  shunt  field  wire  passes 
through  the  frame  at  "F"  as  heretofore.  When,  therefore, 
"+  G"  and  "S"  are  used  as  the  main  generator  terminals, 
the  machine  is  running  as  a  shunt  wound  generator,  similarly 
when  "+  G"  and  ":— G,"  it  is  running  as  a  compound  wound 
generator. 

In  the  special  regulator  "C"  the  inner  set  of  buttons  and 
segmental  contacts  control  one  arc,  similarly  the  outer  set 
the  other..  There  are.,  two' similar  regulator  blades  insulated 
from  each  other  and  moving  together,  one  being  elevated 
above  the  other.  With  the  regulator  blade  in  position  No.  1, 


FOR    MANAGERS    AND    OPERATORS  405 

the  generator  is  operating  as  a  shunt  wound  machine  with 
arc  No.  2  shown  open  circuited.  With  the'  regulator  in  posi- 
tion No.  1  and  2,  circuit  "S"  for  the  generator  is  opened  and 
connection  " —  G"  is  used.  The  machine  is  therefore  running 
as  a  compound  wound  machine.  In  passing  over  to  position 
1  and  2  from  arc  1  the  arc  No.  1  (controlled  'by  the  outer  set 
of  contacts)  has  also  inserted  with  series  therewith  just 
enough  ballast  resistance  to  counteract  the  increased  field 
strength  due  to  cutting  in  the  compound  winding. 

This  prevents  a  flicker  on  the  screen  which  would  otherwise 
ensue.  Arc  No.  2  (controlled  by  the  inner  set  of  contacts) 
has  connected  in  series  therewith  its  maximum  resistance. 
This  is  sufficient  to  limit  the  short  circuit  current  when  the 
carbons  of  arc  No.  2  are  brought  together  to  15  amperes. 
By  moving  over  to  the  two  following  buttons  arc  No.  1 
remains  as  it  was  at  Nos.  1  and  2  and  steps  of  resistance  are 
cut  on  arc  No.  2,  thereby  increasing  the  amperage  to  about 
35.  The  regulator  is  allowed  to  remain  in  this  position  until 
the  carbons  of  arc  No.  2  are  well  burned  in,  after  which  the 
regulator  is  quickly  thrown  to  its  final  position  No.  2.  T,his 
extinguishes  arc  No.  1  and  leaves  arc  No.  2  burning  from  a 
straight  shunt  wound  generator. 

To  pass  back  to  arc  No.  1  when  the  reel  is  completed  on 
arc  No.  2  the  inverse  order  is  followed,  the  explanation  be- 
ing identical.  In  this  type  of  machine  the  connections  from 
the  switchboard  to  arcs  Nos.  1  and  2  are  made  from  the 
studs  shown  and  marked  accordingly.  The  entire  function 
of  the  regulator  "C"  in  the  two  arc  machine  is  to  take  ad- 
vantage of  the  perfection  of  both  types  of  machine,  shunt  and 
compound,  during  the  points  in  the  transition  at  which  they 
are  of  greater  value. 


MARTIN  ROTARY  CONVERTER 

Figure  195  shows  a  general  view  of  the  Martin  Rotary 
Converter,  manufactured  by  the  Northwestern  Electric  Com- 
pany. 

According  to  literature  which  I  have  seen  this  device  is 
made  for  25,  30  and  60  cycle,  110,  220  or  240  volt  supplies, 
delivering  60  to  80  amperes  D.  C.  at  the  arc.  Fig.  196 
shows  the  general  construction  of  the  machine. 

The  manufacturers  of  this  device  were  invited  to  supply 
proof  of  its  electrical  efficiency  and  cuts  for  its  description  in 
the  Handbook,  on  the  same  terms  accepted  by  other  manufac- 


406 


MOTION    PICTURE    HANDBOOK 


Figure  195. 


turers,  viz:  supply  the  cuts  and 
assist  in  the  preparation  of  the 
matter.  They  were  invited  to  do 
this  not  once,  but  several  times, 
and  refused.  Therefore  beyond 
showing  what  it  looks  like,  and 
,how  it  is  constructed,  I  can  only 
say  that  I  have  had  both  favorable 
and  unfavorable  reports  as  to  this 
particular  apparatus.  From  such 
information  as  I  have  had  I  believe 
the  machine  is  well  made  mechan- 
ically, but  that  its  electrical  effi- 
ciency is  rather  low,  due  to  the 
fact  that  it  generates  D.  C.  at  70 
volts  and  brakes  down  the  sur- 
plus pressure  with  resistance.  On 
the  other  hand  its  manufacturers 
claim,  and  I  think  their  claim  is 
well  founded,  that  when  their  ma- 
chine is  used  one  reel  can  be  dis- 
solved into  the  other  without  in 
any  way  effecting  the  picture  on 
the  screen;  also  the  resistance  used 
to  break  down  the  surplus  voltage 
makes  the  arc  comparatively  steady 
and  easy  to  handle. 


-3«i 

Figure  196 


FOR    MANAGERS    AND    OPERATORS 


The  Rotary  Converter 


407 


THE    "Wagner    White    Light    Converter"    combines    a 
motor  and  generator  in  one  machine,  having  but  one 
field  and  one  armature  winding.     The  motor  action 
is   that  of  a  synchronous  motor,  which  makes  it  necessary 
that  the  armature  be  brought  up  nearly  to  full  speed  before 
it   can   be   run   as   a    synchronous   motor.     The    machine    is 
built  for  single,  two  or  three  phase  circuits,  and  for  25,  SO 
and  60  cycle  current,  of  any  voltage  from  110  to  550.     The 
direct  current  voltage  is  65  to  75,  and  the  amperage  capacity 
of  the  various  sizes  35,   50,  70,  90  and  100  amperes.     The  35 
ampere  converter  is  intended  for  use  in  theatres  where  but 
one  projection  machine   (one  arc)   is  used.     The  50  ampere 
size  may  be  used  in  theaters  having  two  projectors,  provided 
the  two  arcs  be  not  burned  simultaneously  for  a  period  of 
more  than  two  minutes. 


Plate  1,  Figure  197. 

Plate  1  is  a  view  of  the  Wagner  single  phase  converter. 
Plate  2  is  a  view  of  the  same  machine  disassembled  to 
show  the  construction  and  parts.  The  mechanical  con- 
struction of  the  single,  two  and  three  phase  converters  is 
practically  identical,  except  as  to  the  number  of  slip  rings 
and  brushes. 


408 


MOTION    PICTURE    HANDBOOK 


By  reference  to  Plate  2,  the  following  parts  are  desig- 
nated by  number:  2,  A.  C.  or  slip  ring  brushes;  3-3,  end 
plates;  4,  slip  ring  brush  leads;  5,  frame;  6  stator  or  field 


Plate  2,  Figure  198.     . 

windings;  7,  armature  shaft;  8,  slip  rings;  9,  ventilating 
fans;  10,  armature;  11,  D.  C.  commutator;  12,  ID.  C.  leads; 
13-13,  main  bearings;  14,  D.  C.  brushes  arid  brush  holders. 

The  armature  shaft,  7,  P.  2,  runs  in  bronze  bearings 
13-13,  P.  2,  and  underneath  these  bearings  are  oil  cham- 
bers from  whence  a  constant  supply  of  oil  is  fed  to  the 
bearings  by  rings.  See  Fig.  179.  These  bearings  are 
mounted  in  end  plates,  3-3,  P.  2,  which  are  single-piece 
castings,  bolted  solidly  to  main  frame  5,  P.  2,  thus  insur- 
ing rigidity  and  freedom  from  vioration.  The  shaft  pro- 
jects from  the  bearings  at  either  end  a  sufficient  distance 
to  accommodate  a  pulley,  so  that  when  not  generating 
direct  current  the  converter  may  be  used  as  a  motor  for 
driving  light  machinery,  such  as  ventilating  fans.  It  is  not 
intended,  however,  that  the  converter  be  used  to  drive 
machinery  and  generate  direct  current  at  the  same  time.  To 
attempt  this  might  cause  overload  which  would  probably 
do  serious  injury  to  the  armature  windings. 

Once  the  converter  has  been  started  it  requires  no  further 


FOR    MANAGERS    AND    OPERATORS 


409 


attention,  unless  the  power  should  for  any  reason  be  cut  off 
for  an  appreciable  period,  in  which  case  it  will  be  necessary  to 
restart  the  motor. 

Plates  3  and  4  are  wiring  diagrams  of  single  phase  con- 
verters, the  only  difference  being  dn  the  starting  switqji. 
Single  phase  converters  may  be  furnished  with  either  three 


OnnectiOn  Diagram 

•.OPERATING  SINGLE  PHASE   CONVERTER 
FOR  MOVINQ    PICTURE   ARCS 
AOE    CXCITATION)        ' 

TOA.C.  LINE 

FOSE 


I  SWITCH*! 


Fuse  and  switch  *i 
rto  be  for-nisKe-d  by 
customer-. 


INSTRUCTIONS  FOS  STARTING 
Before  starting  see  that  all 
switches   are  open. 
I.  CLOSE  switch  'I. 
ZTHROW-main  switc ..    „ 
starting  position  *2  and 
leave  for  approximately 
5  aeco-nels. 
d  THROW -main    switch  to 

-running  position  *3. 
•4  CLOSE  switch  <4-.    If 


Connect   J   to  S* 
Connect  N  to  Ss 
If  DC.  volts  are  too  low 
connect  J   to  Si    &. 

h;9her  number. 
If  DC  volts  are  too  h,qh 
connect    J    to  Sz  *. 
N  to  S-»    or  r,e.»t 


3W(tch  *|,  wait  till  converter 
stops,  then  open  main  A  pole 
switch. 

Connection  Diagram  for  Single  Phase  Converter. 

Plate  3,  Figure  199. 

and  four  pole  starting  switches,  and  both  diagrams  are, 
therefore,  given  here.  Plate  5  shows  the  wiring  of  a  two 
phase  converter  and  Plate  6  of  a  three  phase  converter. 

Single  phase  converters  are  furnished  with  a  single  trans- 
former, while  two  and  three  phase  converters  are  furnished 
with  two  transformers  each.  Wagner  converters  must  take 
their  A.  C.  supply  through  transformers,  as  they  are  wound 
to  operate  at  a  certain  definite  ratio  between  the  A.  C.  supply 
and  the  D.  C.  delivery  voltage,  hence  the  voltage  of  the 
supply  must  be  "stepped  down"  to  that  pressure  which  will 
cause  the  converter  to  deliver  D.  C.  at  the  required  voltage. 
This  plan  has  one  big  advantage  in  that,  should  the  voltage 
of  the  A.  C.  supply  be  altered  at  any  time,  as  for  instance 
from  110  to  220, 'the  only  part  of  the  equipment  it  would  be 
necessary  to  change  would  be  the  transformer  or  transformers. 

By  examining  the  wiring  diagrams  and   Plate  7  it  will  be 


410 


MOTION    PICTURE    HANDBOOK 


noted  that  a  number  of  connections  may  be  made  at  the 
transformer  by  means  of  which  one  may  raise  or  lower  the 
A.  C.  supply  voltage  of  the  converter.  These  connections 
are  marked  SI,  S2,  S3,  S4,  S5,  and  S6  in  the  diagrams  and  on 
Plate  7.  This  arrangement  gives  an  available  range  of  vol- 
tage from  65  to  75  on  the  D.  C.  side  of  the  converter,  or 
allows  one  to  maintain  the  voltage  at  any  required  point  in 
case  the  alternating  current  supply  voltage  is  variable.  The 
wiring  diagrams  explain  the  method  of  using  these  taps. 


Connection  Di»or»rn 


and  switch  '1 
ba  furnished,  by 


INSTRUCTIONS  FOR  STARTING 

Before  starting  see  that  all 

Switches  are,  open. 
I  CLOSE   switch  'I 
2.THROW -main  switch  to 

Starting  position  'Z  and 

leave  for  approximately 

5  seconds 
3  THROW  main  switch  to 

running  position   '3. 
4CL03E   switch    '<*     If 

current  is  reversed,  throw         Note:-  Select  Size  of  w.re  corr,9- 

sw.tcK     4  to  the  other  ponding   to  the    leads    to  which 

pos.tion  wire    is  to    be  Connected. 

S  TO  STOP  converter,  open 

switch- 'I,  wait  till  converter 

stops  then  open-main   3  pole 

3w,tcV 

Connection  Diagram  for  Single  Phase  Converter. 

Plate  4,  Figure  200. 

.  The  Wagner  converter  may  be  used  with  any  one  of  five 
different  styles  of  resistance  (rheostat)  especially  designed 
for  this  equipment,  the  same  being  designated  as  follows: 
Non-adjustable  for  single  arc,  Non-adjustable  for  multiple 
arc,  Adjustable  for  single  arc,  Adjustable  for  multiple  arc, 
and  Duplex  arc  regulator. 

It  is  hardly  necessary,  I  think,  to  enter  into  explanation  of 
these  resistances,  with  the  exception  of  the  "Duplex  Regu- 
lator." This  resistance  is  so  connected  that  the  moving  of 
a  single  handle  introduces  by  gradual  steps  the  full  value  of 
the  resistance  into  the  circuit  of  one  arc,  at  the  same  time 
reducing  the  resistance  in  the  circuit  of  the  other  arc  to  a 


FOR    MANAGERS    AND    OPERATORS 


411 


minimum,  thus  maintaining  a  uniform  load  on  the  converter 
during  the  process  of  fading  one  picture  into  another;  i.e., 
changing  from  one  projection  machine  to  the  other. 

The  Wagner  converter  generates  D.  C.  at  from  65  to  75 
volts,  hence  it  is  necessary  to  use  sufficient  resistance  to 
break  down  this  voltage  to  that  of  the  projection  arc,  which 
varies  from  45  to  55.  This  resistance  serves  the  purpose  of 
a  steadying  ballast,  making  the  arc  steady  and  easy  to  handle. 

STARTING    4  OPERATING     THREE    PHASE    CONVERTER 

FOR  MOVING    PICTURE    ARCS 


Connect  J  toS2(Tr«n»former»0 
Connect  K  toS,  OV.nsf  ormer«  » 
Connect  L  to  S2  (Transformer *2) 


Z.THROWmo.r,  switch  to  runni. 

po.itior.-2. 
3  CLOSE  sw.tch  '3. If  current  , 


« TO  STOP  co 
Not*   Three 


other 
3  pole 


ph.se  i.ne  leads   m<tet   bo  connected 
to  the  main  3  pole:  switch  so  A«  to  qive  clockwise 

•t.rts   ,n  the    wron,   d.rect.on   ch.nge  over  any  two 
of  the  three  (,„.  |..d.  „,  th.  mm,n  3  pole  .Jtch. 

Connection  Diagram  for  Two  Phase  Converter. 

Plate  5,  Figure  201. 

Installation. — Place  the  machine  on  a  firm,  level  foundation, 
in  a  clean,  light  place,  high  enough  from  the  floor  so  that  it 
may  readily  be  kept  clean,  and  so  that  dust  and  litter  cannot 
accumulate  under  it.  Install  the  machine  far  enough  from 
the  wall  so  that  it  will  be  accessible  from  either  end.  See 
General  Instruction  Nos.  1  and  2. 

Wiring. — The  wiring  from  the  converter  to  the  control 
board  (on  starting  switch)  must  be  done  according  to  local  and 
underwriters'  rules.  A  diagram  of  connections  is  sent  with 
each  converter,  and  is  printed  herewith,  which  diagram 
must  be  strictly  followed.  The  connecting  cables  for  an  ordinary 
length  of  run  should  be  at  least  as  large  as  the  corresponding 
converter  leads.  If  the  run  is  a  long  one  the  cables  should  be 
larger. 


412  MOTION    PICTURE   HANDBOOK 

Oiling.— A  moderately  heavy  mineral  bearing  oil  should 
be  used,  and  the  oil  should  be  changed  after  each  200  hours 
of  run.  The  oil  level  in  the  oil  box  should  be  kept  about 
one-quarter  inch  below  the  lower  part  of  the  shaft.  See 
General  Instruction  No.  3. 

Brushes  and  Care  of  Commutator. — Before  starting  a  new 
machine,  examine  end  plate  on  commutator  side  and  see 
that  the  small  pointer  fixed  on  the  end  plate  is  opposite  the 
chisel  mark  on  the  rocker  arm  carrying  the  brushes.  If  it 
is  not  then  move  rocker  arm  until  it  is. 

Should  the  brushes  begin  to  spark  under  normal  load  it 
will  probably  be  found  that  the  commutator  has  worn  un- 
evenly and  needs  smoothening.  Procure  a  sheet  each  of 
coarse  and  fine  sandpaper,  preferably  garnet  sandpaper. 
Do  not  under  any  circumstances  use  emery  paper  or  emery  cloth. 
(This  stunt  is  recommended  by  the  manufacturer,  not  me. — 
Author.)  Obtain  a  flat  piece  of  wood  about  the  same  width 
as  the  commutator;  place  the  coarse  sandpaper  around  it 
and  hold  against  the  commutator  when  machine  is  running. 
Give  the  sandpaper  just  enough  lateral  (side)  movement  so 
that  all  parts  of  the  commutator  may  be  smoothed  down 
evenly.  When  the  rough  places  are  all  out,  complete  the 
smoothing  process  with  fine  sandpaper,  using  lighter  pres- 
sure. See  General  Instruction  No.  8. 

Fitting  Brushes. — When  it  is  necessary  to  fit  new  brushes, 
proceed  as  follows :  With  the  machine  stationary,  and  the 
brushes  fitted  into  the  brush  holders,  a  piece  of  coarse  sandpaper 
is  placed  on  the  commutator,  rough  side  toward  the  brushes,  and 
grasping  the  sandpaper  with  one  hand  each  side  of  the 
commutator,  pull  the  sandpaper  rapidly  back  and  forth  and 
the  brush  will  be  ground  down  and  take  the  same  curve  of 
the  commutator.  See  General  Instruction  No.  8. 

The  brushes  used  on  this  machine  are  made  especially  for 
it,  and  are  a  mechanical  mixture  of  metallic  copper  and  carbon. 
When  new  brushes  are  required  they  should  be  purchased  from 
the  Wagner  Electric  Manufacturing  Company. 

Starting  a  New  Machine. — After  the  installation  and  wir- 
ing has  been  completed,  look  well  to  the  follwing  points: 
(1)  See  that  the  A.  C.  line  fuses,  are  in  place.  (2)  See 
that  the  converter  oil  boxes  are  filled  with  oil.  (3)  See 
that  the  pointer  on  the  end  plate  coincides  with  the  chisel 
mark  on  the  rocker  arm  carrying  the  brushes.  Everything 
is  now  ready  for  starting  up  and  the  instructions  which  are 
sent  out  with  each  converter  (and  printed  here)  should  be 
carefully  studied.  See  that  all  switches  are  in  the  open  position, 


FOR    MANAGERS    AND    OPERATORS 


413 


then:  (1)  Close  A.  C.  line  switch.  (2)  Throw  main  four-pole 
switch  (or  three-pole  as  is  the  case)  to  starting  position,  and 
leave  for  approximately  five  seconds.  (3)  At  end  of  five  seconds 
throw  main  switch  to  running  position.  (4)  Close  polarity 
changing  switch  either  way.  (5)  Bring  the  arc  lamp  carbons 
together,  and  quickly  draw  them  apart  to  start  the  arc. 

On  account  of  the  peculiar  characteristics  of  the  converter  the 
polarity  of  the  .arc  lamp  may  at  times  be  reversed  in  starting, 
and  it  is  therefore  necessary  that  a  polarity  reversing  switch  be 


INSTRUCTIONS  FOR  STARTING. 
Before  starting  see  that  all  switches 
are   open. 
LtHROW  main  switch  te  start  m, 

rition^l  and  leave  for  approximately 
seconds-. 
2.THROW  main  awit  ch  te  runnine, 

position  »2. 

3. CLOSE  switch *3.If  current  is 
reversed,  throw  switch  *3  to  the  other 
position^ 

•4.TO  STOP,  converter  open  main*  r°l« 
switch.    '•   . 

Motet  L.t*'.tjgtd9  must  be  connected 
to  the  mmin/A  pole  switch  so  as  to  give 
(from  correlator  end)  direction  of  rotation;^  maehiM 
starts  in  the  wrong  direction  change  over 
line  leadj   of  one  phase  on  the  rnain  4  pole  switch. 


TRANSFORMER** 

Connect  J  to  S|  (Transformer^)  . 
Connect  K  t.S,  frnjn,f.m«re  «<*Z) 
ConnertL  toSzCTrensforiner'2l 
If  D.C. volts  are  too  low,  connect  K  to  lesds  £«  of 
transformers »1*^,and  leads  J »-Lto Sj or  S,. 

If  D.C.  volts  are  too  hio,h,connect  Kto  leads  Si  of 
transformers*!  *x-*fe,a.nd.  i«uts  J  », L  to  St  or  St. 

Thdis 

leadste 


omWred  leads.  eeen  «n  its  c«vn  trM»f«rmer.Th 

oth  to  S,,  both  to  St,  or  both  to  Sj. 

Note.-  Select  size  «f  «,r.  corretpondinj  to  the 


. 
which  wtre  i«to  be  connected 


Connection  Diagram  for  Three  Phase  Converter. 

Plate  6,  Figure  202. 

included  between  the  D.  C.  resistance  and  the  arc.  This 
switch  is  shown  in  Plate  4.  After  starting  the  converter  and  arc, 
if  it  is  found  that  the  polarity  is  reversed  and  the  crater  is 
forming  on  the  negative  carbon,  the  polarity  switch  should 
be  thrown  over.  (6)  To  stop  converter  open  switch  1,  wait 
until  the  converter  stops,  and  then  open  main  four-pole  switch. 
It  sometimes  happens  that  trouble  is  experienced  in  start- 
ing the  converter  for  the  first  time.  The  most  common 
sources  of  trouble  are:  Converter  will  not  start  after  clos- 
ing A.  C.  line  and  throwing  three  or  four  pole  switch  to 
starting  position.  This  may  be  caused  by  any  one  or  more 
of  the  following  things:  (a)  A.  C.  line  fuses  either  not  in 
place  or  faulty,  (b)  Switch  contacts  not  making  good  con- 


414 


MOTION    PICTURE    HANDBOOK 


tact  with   the   switch   jaws,     (c)    Brushes  lifted   off   commu- 
tator,    (d)  Mistakes  in  connecting  up. 

If  no  trouble  is  experienced  in  getting  the  converter  started 
it  sometimes  happens  that  the  fuses  blow  upon  throwing  the 
four-pole  switch  over  into  starting  position.  This  may  be 
caused  by  switching  over  before  the  motor  has  attained  its 
full  speed.  Until  the  operator  gets  experience  in  estimating 
the  correct  motor  speed  it  is  advisable  for  him  to  time  himself. 
On  the  other  hand,  too  long  an  interval  must  not  be  allowed  or 
the  converter  will  pass  the  synchronous  speed.  It  is  ex- 
pected that  five  seconds  will  bring  the  armature  up  to  proper 
synchronous  speed. 


Plate  7,  Figure  203. 

If  the  converter  stops  after  switching  into  running  posi- 
tion 3,  examine  the  slip  ring  brushes,  also  the  transformer 
connections,  and  see  that  the  switch  blade  and  jaws  are 
making  good  contact.  If  a  vicious  sparking  is  seen  on  the 
commutator  it  indicates  a  break  in  some  of  the  connections 
running  to '  leads  A,  B,  C,  D,  Plates  3,  4,  5  and  6.  This 
trouble  can  be  readily  recognized  if  a  polarized  D.  C.  volt- 
meter is  connected  across  leads  G  and  H.  It  is  evidenced 
by  a  periodic  swing,  forward  and  back,  of  the  voltmeter 
needle.  If  there  is  continuous  sparking,  the  switch  contacts 


FOR    MANAGERS    AND    OPERATORS  415 

and  blades  connecting  to  converter  leads  E  and  F  should 
be  examined  and  any  faulty  contact  made  good.  If  this  does 
not  remedy  matters  the  trouble  may  be  due  to  commutator 
being  rough,  though  this  is  not  a  trouble  to  look  for  in  a 
new  machine.  It  has  been  assumed  that  the  operator  has 
made  sure  that  the  pointer  on  the  end  plate  is  opposite  the 
chisel  mark  on  the  rocker  arm,  as  sometimes  the  rocker 
arm  gets  displaced  during  shipment,  and  such  displacement 
will  cause  sparking. 

Hallberg's  D.  C.  to  D.  C.  Economizer 

THE   Hallberg  D.   C.   to   D.   C.   Economizer  consists  es- 
sentially  of   a    D.    C.    motor    which    pulls    a    specially 
wound  generator  delivering  current  to  the  arc  at  arc 
voltage,  without  any  resistance  in  series.     The  only  waste  is, 
therefore,    that   consumed   in    the   machine    itself.      In    other 
words  it  costs   more   than    the  rheostat,   but    saves   the    dif- 
ference between  its  efficiency  and  the  efficiency  of  the  rheo- 
stat.    This  is  very  great  on  voltage  of  220  or  more,  and  is 
considerable  on  110.    The  manufacturer  claims  the  following: 

HALLBERG  DIRECT  CURRENT  ECONOMIZER  DATA 

, Line  Input —     — ,  , Output  at  Arc » 

Line  Line 

Fuses        Line    Am-     Line  Arc             Arc             Arc      Watts     Em- 
Required.  Volts,  peres.  Watts.  Voltage.  Amperes.    Watts.     Loss,  ciency. 

20A      110      17      1,870         50-55  30      1,650      220      88% 

10A      220      10      2,200          50-55      30-35      1,650      550      75% 

5A      550       4      2,200         50-55      30-35      1,650      550      75% 

The  table  or  data  is  explicit,  and  if  the  manufacturer  will 
base  the  payment  of  his  bill  upon  the  accuracy  of  the  figures 
given  the  machine  ought  to  prove  a  good  investment  even 
for  110  volt  current,  since  the  control  of  D.  C.  through  a 
rheostat  is,  as  we  all  know,  enormously  wasteful.  A  rheostat 
has  considerably  less  than  50  per  cent,  efficiency. 

Fig.  204  illustrates  the  general  make-up  of  the  110  volt  type  of 
economizer,  which,  while  being  constructed  along  the  lines  of  a 
motor  generator,  is  in  the  strict  sense  of  the  word  only  in  part 
a  motor  generator.  The  principle  involved  is  original  with  Mr. 
Hallberg  and  permits  the  use  of  a  smaller  and  more  efficient 
motor  and  generator  than  would  be  possible  were  the  apparatus 
a  straight  motor  generator  set.  The  110  volt  outfit  is  provided 
with  an  automatic  starting  box  and  light  controller  by  means 
of  which  the  operator  can  vary  the  amperes  at  the  arc  anywhere 


416 


MOTION    PICTURE   HANDBOOK 


from  20  to  30,  on  the  25  ampere  size ;  from  30  to  40  amperes  on 
the  35  ampere  size,  and  from  40  to  60  on  the  50  ampere  size.  It 
is,'  of  course,  possible  to  secure  lower  ampere  output  than  speci- 
fied as  a  minimum  with  any  of  the  above  machines  by  the  use 
of  special  controllers,  which  can  be  furnished  upon  request. 
Fig.  205  illustrates  the  Hallberg  D.  C.  economizer  as  made  for 
voltages  ranging  from  200  to  750.  This  outfit  is  a  straight  motor 


LINE  ruses 
15AM  PS.  row  I  (0  VOL.T& 
10    •         •   220    • 
5     •         -   550 


CURRENT  AT  ARC 

tS  ADJUSTABLE 

FROM  2O  TO 


Figure  204. 

generator  set,  in  which,  however,  the  generator  is  of  special  con- 
struction delivering  a  steady  ampere  flow  to  the  arc  without  the 
use  of  a  rheostat.  The  200  to  750  volt  outfit  is  also  furnished 
complete  with  automatic  starter  and  light  controller,  and  be- 
sides this  outfit  has  a  pully  coupling  between  the  motor  and  gen- 
erator on  which,  in  special  cases,  a  belt  may  be  placed  for  driving 
the  economizer  by  means  of  an  engine,  which  would  make  the 
economizer  operate  a  motion  picture  arc  just  as  it  does  when 
driven  from  an  electric  circuit,  and  at  the  same  time  from  the 
high  voltage  side  current  can  be  taken  for  driving  fan  motors, 
or  a  limited  number  of  lamps.  This  is  an  important  feature  and 
might,  under  some  circumstances,  be  of  considerable  value  to  an 
exhibitor. 

Another  feature  of  construction  is  that  the  low  voltage  side  of 
the  economizer  is  a  separate  unit  which  can  be  run  as  an  ordinary 
dynamo  by  an  engine  ranging  from  3  to  6  horsepower  in  capacity 


FOR    MANAGERS    AND    OPERATORS  417 

for  the  operation  of  a  motion  picture  arc.  The  other  half  of  the 
machine,  representing  the  high  voltage  side,  is  an  ordinary  elec- 
tric motor  which  can  be  taken  off  its  base  in  a  few  minutes'  time 
and  used  as  a  regular  electric  motor,  together  with  its  automatic 
starter.  These  are  points  of  economy  which  represent  certain 
advantages  to  the  purchaser  of  this  class  of  apparatus.  It  is  not 
practical  to  give  wiring  diagrams,  showing  the  connections  for 
these  machines,  because  they  vary  for  different  voltages  and  cur- 


Figure  205. 


rents,  and  as  these  machines  are  generally  built  to  specifications 
to  suit  the  individual  operator  or  manager,  it  is  best  to  depend 
upon  the  blue  print  and  diagram  of  connections  which  accompany 
the  shipment,  and  if  the  instructions  should  be  lost,  another  set 
can  be  readily  obtained  at  the  office  of  the  manufacturer. 

INSTRUCTION  FOR  SETTING  AND  OPERATING 

1.  Installation.     (See  General   Instruction   Nos.   1   and  2.) 

2.  Connections. — All  connection  should  be  made  as  shown 
in  the  wiring  diagram  sent  with  each  machine.     They  must 
be  clean  and  tight.     Fuses  should  not  have  a  higher  capacity 
than  that  indicated  by  the  diagram. 

3.  Brush  Tension. — After  the  machine  has  been  properly 
set  and   connected,  rotate  the  armature  by  hand   and  examine 
each  and  every  carbon  brush  to  make  sure  that  it  moves  freely, 
without  the  slightest  friction  in  the  brushholder  which  guides  it. 
Make  sure  that  the   flexible  copper  cable,   or  pigtail,   as   it  is 
called,  is  properly  clamped  by  the  screw  in  the  brushholder  cast- 
ing provided  for  that  purpose.    When  the  brush  is  in  proper  con- 
dition  and   moves   freely   in  the  holder,  the  next  point  to  be 
looked  after  is  the  spring  tension  which  pushes  the  brush  against 
the    commutator.      See    General    Instruction     No.    8.      The 


418  MOTION    PICTURE   HANDBOOK 

brush  tension  spring  is  adjustable  by  putting  the  end  of  it  in  the 
different  notches  provided  for  it  in  the  brushholder  casting,  and 
any  degree  of  tension  can  be  had  by  using  the  different  notches. 

4.  Oiling. — The  oil  chambers  should  contain  enough  oil  to 
give  the  rings  a  good  dip.    The  oil  level  will  be  seen  in  the  gauge 
on  the  sides  of  the  bearings  and  should  be  merely  at  the  top  of 
the  gauge.     When  starting  the  machine,  lift  oil  chamber  covers 
and  see  that  the  oil  rings  are  turning  freely  and  carrying  oil  to 
the  shaft.     The  old  oil  should  be  drawn  off  by  unscrewing  the 
drainage  plug  at  bottom  of  the  bearing  every  month  or  two,  and 
replaced  with  new  oil.     See  General  Instruction  No.  3. 

5.  Setting   of   Brushes. — Machines   are   shipped   from  the 
factory  with  the  brushholders  and  brushes  properly  set.    The 
position  of  the  brushes  is  approximately  half  way  between  the 
poles.     In  the  motor,  they  are  placed  one  or  two  segments  back 
(that  is,  against  the  direction  of  rotation)  of  the  exact  middle  or 
neutral  point,  while  in  the  generator  .they  are  set  one  or  two  seg- 
ments forward.    The  brushholders  should  be  placed  on  the  studs, 
so  that  the  brushes  will  not  run  in  the  same  line  on  the  commu- 
tator.   This  will  help  to  avoid  grooving. 

6.  Starting    Set.— First    see    that   the    starting   box    lever 
has  moved  back  to  the  off  position.    If  there  is  a  regulating  rheo- 
stat on  the  motor  end,  its  handle  should  be  moved  as  far  as  possi- 
ble in  a  contra  clockwise  direction.    If  there  is  one  on  the  gen- 
erator end,  its  handle  should  be  moved  as  far  as  possible  in  a 
contra  clockwise  direction.     Close  the  main  switch  and  move  the 
lever  of  the  starting  box  over  the  contacts,  taking  about  one  sec- 
ond for  each,  until  it  is  against  the  magnet  which  will  hold  it. 
If   the   set  has   not   started  when   the   fourth   contact  point   is 
reached,  open  the  main  switch  and  ascertain  the  trouble.    When 
the  set  is  running,  the  current  may  be  adjusted  by  means  of 
the  regulating  rheostats. 

7.  Stopping  Set. — Open  the  main  switch  and  let  the  start- 
ing box  operate  itself.     The  lever  will  be  released  when  the 
motor  has  slowed  down,  when  it  will  fly  back  to  the  "off"  posi- 
tion.    If  the  contacts  become  rough  and  prevent  the  lever  from 
moving  fully  back,  they  should  be  cleaned  with  very  fine  sand- 
paper.    The  lever  should  never  be  fastened  or  allowed  to  stick 
at  an  intermediate  point. 

8.  Care  of  Brushes  and  Commutator.     (See   General   In- 
struction No.  8.) 


FOR    MANAGERS    AND    OPERATORS  419 

Hallberg's  Twentieth  Century  Motor- 
Generator  Set 

JH.  HALLBERG,  New  York,  has  put  out  a  motor  gen- 
9      erator  set,  the   general  design   of  which  is   shown   in 
Plate  1,  Fig.  206.     The  machine  occupies  a  floor  space 
15  by  31   inches,  and  is   15  inches  in   height.     Its  weight  is 
a  little  less  than  500  pounds  in  the  70  ampere  size,  the  40  and 
130  ampere  machines  being  respectively  less  and  greater  in 
weight.     The  machine  is  compact,  rigid  in  construction,  and 
its  parts  are  easily  accessible  for  adjustment  or  repair,  as  is 
made  evident  through  an  examination  of  the  various  plates. 
The  machine  is  made  in  capacities  of  20-40  amperes,  30-70 
amperes,    and    60-130    amperes.      The    30-70    ampere    size    is 
the    capacity   more    largely    in    demand    for    moving   picture 


Plate  1,  Figure  206. 

work,  in  that  it  will  operate  with  a  fair  degree  of  efficiency 
on  a  30  ampere  load,  and  will  carry  two  50  ampere  arcs  for 
the  short  period  of  time  necessary  to  make  a  change  from 
one  machine  to  the  other.  It  must  not  be  understood  from 
this  that  the  generator  will  stand  up  under  a  100-ampere  load 
for  more  than  one  to  one  and  a  half  minutes. 

The  machine  delivers  direct  current  to  the  arc,  at  arc 
voltage,  without  any  resistance  interposed  in  the  circuit, 
which  means,  of  course,  that  it  is  a  specially  compounded 
generator,  and,  to  go  a  little  further,  a  specially  compound- 


420  MOTION    PICTURE   HANDBOOK 

ed  generator  pulled  by  an  A.  C.  motor,  the  two  armatures 
being  mounted  on  one  shaft,  and  contained  in  one  housing, 
with  a  ball  bearing  at  either  end  of  the  shaft,  both  being  "ball 
bearings." 

Plate  1  supplies  a  view  of  the  whole  machine,  with  the 
various  parts  numbered. 

No.  1. — Lubrication.  The  lubrication  of  this  machine  dif- 
fers from  that  of  most  other  motor-generator  sets  used  for 
moving  picture  work,  in  that  grease  is  used  instead  of  oil. 

The  grease  chambers  may  be  filled  in  two  ways:  first,  if 
you  have  purchased  your  grease  in  a  "gun,"  or  if  you  have 
a  "gun"  which  can  be  filled  with  grease,  having  removed 
screw,  23,  Plate  1,  and  a  similar  one  on  the  opposite  diameter 
of  the  grease  chamber  cover,  you  can  place  the  spout  of 
the  gun  in  the  upper  hole  and  force  grease  in.  This  will 
force  the  old  grease  out  at  the  lower  hole,  and  the  job  will 
be  a  fairly  complete  one.  This  operation  must  be  performed 
for  the  grease  chamber  at  each  end  of  the  armature  shaft. 
When  through  you  will,  of  course,  replace  the  screws. 

Another  way  is,  if  you  have  no  grease  gun,  to  remove 
screws  24  (four  of  them),  on  the  end  of  the  cast  iron  cap 
which  covers  the  grease  chamber.  You  can  then  pull  the 
cap  off,  clean  out  the  old  grease,  and  pack  the  chamber  with 
fresh  lubricant.  Where  this  is  done  it  would  be  well  to 
wash  out  the  grease  chamber  thoroughly  with  kerosene  or 
gasoline. 

Still  a  third  way  is  to  remove  screw,  No.  23,  Plate  1,  and 
insert  in  lieu  thereof  a  compression  grease  cup  having  a  stem 
of  the  same  diameter  and  thread  as  a  one-eighth  inch  gas 
pipe.  Where  the  compression  grease  cup  is  used  when  it  is 
desired  to  force  grease  in  it  will  be  necessary  first  to  remove 
the  screw  in  the  opposite  diameter  to  screw  23,  Plate  1, 
same  being  immediately  below  the  grease  cup,  in  order  to 
allow  an  equal  amount  of  old  grease  to  flow  out.  Where  the 
compression  grease  cup  is  used  it  is  merely  designed  that 
the  cup  take  the  place  of  a  grease  gun — therefore  it  should 
be  a  large  one  and  only  used  to  force  a  large  quantity  of 
grease  in  about  once  every  60  to  90  days,  it  being  expected 
that  when  the  run  is,  say,  twelve  to  fourteen  hours  per  day 
one  greasing  will  last  for  that  length  of  time. 

Caution:  Don't  use  any  and  every  kind  of  grease.  The 
grease  serves  ball  bearings,  and  if  it  contain  alkalis  or  acids 
you  may  expect  trouble  and  plenty  of  it.  For  this  reason  my 
advice  is :  Use  only  grease  procured  from  the  manufacturer 
of  the  machine.  You  may  regret  it  if  you  do  otherwise. 


FOR    MANAGERS    AND    OPERATORS  421 

No.  2. — Locating  the  Motor  Generator.  (See  General  In- 
struction No.  1.) 

No.   3. — Installation.     (See   General   Instruction  No.  2.) 

No  4. — Cleanliness.     (See  General  Instruction  No.  4.) 

No.  5. — Loose  Connections.  (See  General  Instruction  No. 
6.) 

No.  6. — Ammeter  and  Voltmeter.  (See  General  Instruc- 
tion No.  7.) 

No.  7.— Removing  End  Bearing  Bracket  2,  P.  1.  It  will 
never  be  necessary  to  remove  this  bracket  unless  some  fault 
should  develop  through  the  use  of  improper  grease,  or  a 
very  improbable  inherent  imperfection  in  the  ball  bearings, 
but  should  such  a  thing  occur  you  may  remove  end  bearing 
bracket  2,  P.  1,  by  first  removing  four  hexagon  shaped  nuts, 
holding  the  cast  iron  cover  of  the  grease  chamber.  These  nuts 
do  not  show  in  the  plates,  but  correspond  to  nuts  24,  P.  1,  in  the 
grease  chamber  cover  at  the  opposite  end  of  the  machine.  The 
studs,  which  are  held  by  four  hexagon  nuts,  not  only 
hold  the  outside  cast  iron  cover  to  the  grease  chamber,  but 
extend  through  and  into  an  inside  cast  iron  grease  chamber 
cover.  The  ball  bearings  are  clamped  between  these  two 
end  covers,  and  these  bearings  should  never  be  removed 
from  the  armature  shaft  except  it  be  desired  to  install  a  new 
bearing.  Therefore,  after  having  removed  the  hexagon  nuts 
and  the  outside  cover,  using  a  copper  punch  and  hammer, 
gently  drive  the  studs  inward  to  loosen  the  inside  cover. 
Having  done  this,  remove  bolts  4,  P.  1  (four  of  them),  where- 
upon you  may  pull  away  end  bearing  bracket  2,  P.  1. 

No.  8. — To  Remove  the  Ball  Bearing  at  the  A.  C.  end  of 
the  armature,  follow  Instruction  No.  7.  Having  done  so  you  will 
see  on  the  end  of  the  shaft  a  nut  having  in  its  edge  a  saw 
kerf,  and  in  its  face  the  head  of  a  machine  screw.  This 
screw  acts  as  a  lock  nut  by  compressing  the  edges  of  the 
nut  where  the  saw  kerf  is  made,  thus  locking  the  threads  to 
the  shaft.  Loosen  it  and  remove  the  nut,  which  has  a  right- 
hand  thread.  This  will  release  the  ball  bearing,  which  may 
be  pulled  out.  When  installing  the  new  ball  bearing  or  re- 
placing the  old  one,  be  sure  and  get  it  on  the  shaft  straight  or 
"square."  If  you  attempt  to  put  it  on  a  slant  it  won't  go, 
but  if  started  on  just  right  will  slip  on  easily.  Having  it  in 
place,  set  up  the  lock  nut  as  tight  as  you  can  get  it,  and  then 
set  up  the  screw  in  its  face,  thus  locking  the  nut  to  the  shaft. 
In  replacing  end  bearing  bracket  2,  P.  1,  proceed  carefully, 
and  don't  try  to  force  it  on  over  the  ball  bearing.  When  you 
get  it  exactly  right  it  will  slip  on  without  any  trouble  what- 


422 


MOTION    PICTURE    HANDBOOK 


ever.  If  it  does  not  do  so,  that  is  your  fault  and  not  the 
fault  of  the  bracket — you  have  not  got  it  exactly  in  the  right 
position  with  relation  to  the  bearing.  If  you  try  to  force  it 
on  you  will  probably  succeed  in  ruining  the  ball  bearing. 
The  rest  of  the  process  of  replacing  is  simply  the  reversal 
of  the  process  of  disassembling. 

No.  9. — To  Remove  the  Armature  lift  out  all  the  brushes, 
17,  P.  2.  To  do  this  lift  finger  9,  'P.  3,  and  pull  the  brush 

out,  letting  it  hang  by  its 
pig  tail  so  that  you  will  be 
sure  to  get  it  back  in  the 
right  holder.  Next  remove 
bolts  4,  P.  1  (four  of  them). 
Next  remove  the  four  hexa- 
gon-headed bolts,  24,  P.  1, 
holding  grease  cover  cap, 
22,  P.  1,  and  pull  the  arma- 
ture, carrying  end  bracket, 
2,  P.  1,  with  it,  straight  out 
at  the  A.  C.  end. 

Caution:  Never  lay  an 
armature  dozvn  flat  on  any- 
thing. Either  stand  it  on  end, 
or  else  support  it  on  two 
chairs  or  boxes,  using  the 
ends  of  its  shaft  for  the 
purpose.  If  you  lay  the 
armature  itself  down  on  the 

floor  or  table  you  are  likely  to  injure  the  insulation.  The 
replacement  of  the  armature  is  simply  a  reversal  of  the  proc- 
ess of  taking  it  out,  doing  each  step  in  its  turn. 

No.  10.— To  Remove  the  Commutator  End  Bearing  Bracket, 
3,  P.  1,  first  remove  four  hexagon  headed  bolts  24,  P.  1,  in 
grease  cover  cap,  22,  P.  1.  Next  lift  out  all  the  brushes. 
They  may  be  lifted  out  by  raising  finger  9,  P.  3.  Let  them 
hang  by  their  pig  tails,  so  that  you  will  get  them  back  in  the 
right  holder.  Remove  bolts  4,  P.  1  (four  of  them),  where- 
upon the  bracket  may  be  pulled  away. 

Caution:  The  four  hexagon  head  bolts  extend  through 
and  hold  the  plate  covering  the  inside  end  of  the  grease 
chamber.  This  cover  will  sometimes  stick  slightly.  Before 
removing  the  bolts,  but  after  having  backed  them  out  for 
three  or  four  turns,  tap  on  them  lightly  with  a  hammer,  in 
order  to  loosen  the  inside  grease  chamber  cover. 


Plate  2,  Figure  207. 


FOR    MANAGERS    AND    OPERATORS 


423 


No.  11. — To  Remove  Brush  Yoke,  6,  P.  2,  follow  Instruc- 
tion No.  10,  then  loosen  screw,  7,  P.  2,  whereupon  you  may 
pull  away  the  yoke,  carrying  all  the  brush  holders. 

No.  12. — Brush  Holder  Stud.  Should  it  ever  be  necessary 
to  remove  brush  holder  stud,  8,  P.  2,  it  may  be  done  by 
loosening  nut,  10,  P.  2,  but  if  you  do  this,  be  very  careful  in 
reassembling  that  the  insulation,  which  consists  of  two  mica 
washers,  9,  P.  2,  and  a  mica  sleeve  around  the  bolt,  be  not 
in  any  way  injured.  If  this  insulation  is  not  perfect,  then 
the  whole  frame  of  the  machine  will  be  charged  with  po- 
tential. In  loosening  these  parts  it  will  be  well  to  remove 
nut  10,  P.  2,  and  thoroughly  clean  the  contact  between  it  and 
the  copper  clip  to  which  the  wire  is  connected.  In  reassem- 
bling be  sure  to  set  up  nut  10,  tight,  else  you  will  not  have  good 
electrical  contact;  also  it  is  essential  that  the  lock  nut  be- 
hind nut  10,  which  holds  the  insulation  in  place,  be  set  up 
tight,  else  the  brushholder  stud  will  vibrate  and  thus  cause 
trouble. 

No.  13. — Brushholder,  12,  P.  2,  may  be  slipped  off  at  any 
time   by  loosening   screw   16,   P.   2.     Before   taking   off  the 
brushholder  you  should  make  a  scratch  mark  at  its  end  on 
the  stud,  so  that  in  re-f 
assembling     you     may 
get   it   back  in    exactly 
the     same     position     it 
formerly  occupied. 

No.  14.— Care  of  the 
Commutator.  (See  Gen- 
eral Instruction  No.  8.) 

No.  15.— To  Install 
New  Brushes.  First  raise 
finger  16,  P.  1  (shown 
better  at  9,  P.  3),  and 
remove  the  screw  hold- 
ing the  end  of  the  pig 
tail  to  the  brass  cast- 
ing, then  lift  out  the 
brush,  put  in  the  new 
one  and  attach  its  pig 
tail  to  the  casting  the 

same  as  the  old  one  was.  Plate  3,  Figure  208. 

The  face  of  the  new  brush 

must  be  ground  fitted  to  the  curve  of  the  commutator.  To  do  this 
lift  out  all  the  brushes  you  are  not  replacing,  then  place  on 
the  commutator,  sand  side  out,  a  strip  of  No.  1  sandpaper 


424 


MOTION    PICTURE   HANDBOOK 


long  enough  to  extend  one  and  one-half  times  around  its 
circumference.  Lower  the  new  brush  on  this  sandpaper 
under  the  pressure  of  its  tension  spring,  and  revolve  the 

armature  until  the 
brush  is  ground  down 
to  a  proper  bearing.  It 
is  also  possible  to  lay  a 
piece  of  sandpaper  on 
the  commutator  and 
pull  it  back  and  forth, 
but  the  other  way  is 
the  better. 

No.  16.— Heating-  (See 
General  Instruction  No. 

11.) 

No-  17.— General  Re- 
marks. Plate  3  shows 
the  construction  of  the 
brushholder  in  detail, 
14  being  the  pig  tail,  11 
the  spring  which  gov- 
erns the  amount  of 
tension  supplied  ihe 
brushes  through  finger 
9,  P.  3.  Plate  4  shows 
the  pole  piece  con- 
struction, main  poles  AA  being  wound  and  BB  not  wound. 
In  like  manner  interpoles  or  "commutating  poles"  C,  are 
wound,  while  DD  shows  the  core  of  the  poles  without 
the  windings.  The  machine  is  entirely  self-contained,  and 
requires  no  special  base.  It  may  either  be  set  on  a  cement 
floor  and  bolted  down  or  on  any  other  reasonably  solid 
foundation,  but  if  installed  in  the  operating  room  it  should 
be  set  on  a  felt  pad,  as  per  General  Instruction  No.  2.  This 
will  take  up  all  vibration,  make  the  machine  practically 
noiseless,  and  there  will  be  no  necessity  for  bolting  it  down 
at  all. 

The  efficiency  of  the  machine  is  claimed  by  the  manufac- 
turer to  be  between  65  and  70  per  cent,  depending  upon 
local  conditions  and  the  degree  of  intelligent  care  given. 

The  accompanying  connection  diagrams  are  quite  plain, 
and  may,  I  believe,  be  followed  without  any  trouble  by  the 
average  well-posted  operator.  Plate  5  shows  the  various 
connections  for  single,  two  and  three  phase  110  or  220  volt 
circuits. 


Plate  4,  Figure  209. 


FOR    MANAGERS    AND    OPERATORS 


42$ 


All  Hallberg  Twentieth  Century  A.  C.  to  D.  C.  motor  genera- 
tors are  so  wound  that  they  may  be  used  either  for  110  or  220 
volt  current,  merely  by  changing  the  connections  as  shown  in  P.  5. 

Two-Arc  Machine. — P.  6  shows  the  wiring  of  the  D.  C. 
end,  with  two  projection  arcs  connected  in  multiple  with 
each  other.  By  this  arrangement  arc  No.  1  may  be  operat- 
ed at  any  desired  amperage  between  30  and  60  by  moving 
the  handle  of  the  field  controller,  which  has  twenty-one 


DDD 


J 1 


Plate  5,  Figure  210. 

contacts,  supplying  twenty-one  different  current  values.  When  it 
is  desired  to  start  the  second  arc  and  fade  the  first  picture 
into  the  next,  the  operating  or  machine  switch  on  machine 
No.  2  may  be  closed,  and  when  the  time  comes  to  swing 
over  to  that  machine  its  arc  is  started  merely  by  bringing 
the  carbons  together  and  separating  them  in  the  usual  man- 
ner, which  will  automatically  extinguish  the  arc  of  machine 
No.  1,  thus  fading  one  picture  into  the  next.  This  is  a  matter 
which  will  require  some  practice,  but  once  it  is  mastered  it  is 
quite  possible  to  secure  fair  results.  But  where  this  plan  is 
used  the  operator  will  do  well  to  burn  craters  on  his  carbons 
when  there  is  no  picture  on  the  screen.  In  other  words,  ht 
should  have  a  supply  of  burned-in  carbons.  It  will  prob- 


426 


MOTION    PICTURE   HANDBOOK 


ably  also  be  found  necessary  to  recenter  the  upper  crater 
by  raising  the  lamp  about  one-quarter  of  an  inch  before 
starting  the  arc.  The  machine  motor  must,  of  course,  be 
started  at  the  same  time  the  arcs  are  changed  over.  The  man- 
ufacturer claims  that  one  of  the  peculiarities  of  this  genera- 
tor is  that  it  picks  up  and  steadies  its  arc  almost  instantly. 

P.  7  shows  the  machine  connected  to  a  single-phase  cir- 
cuit, with  an  emergency  circuit  of  two  economizers  which 

may  be  put  into  service 
merely  by  throwing 
over  the  upper  three- 
pole  switch.  P.  7  also 
shows  a  switchboard 
upon'  which  is  mounted 
the  controller  shown  in 
P.  6,  by  means  of 
which  the  amperage  at 
the  arc  may  be  varied 
at  the  will  of  the  oper- 
ator, or,  When  two  arcs 
are*  to  be  operated  at 
the  same  time  this  con- 
troller is  used  to  secure 
the  desired  D.  C.  am- 
perage within  the  ca- 
pacity of  the  machine. 
The  lower  three-pole, 
double-throw  switch  in 
P.  7  is  so  connected  that 
when  the  handle  is  to 
the  right,  the  compound 
winding  on  the  gener- 
Plate  6,  Figure  211.  ator  opposes  the  shunt, 

which  causes  the  gen- 
erator to  produce  constant  current  for  the  operation  of  one 
arc  at  a  time,  in  which  case  no  resistance  is  necessary  in 
series  with  the  arc,  the  generator  having  within  itself  the 
necessary  flexibility  to  properly  control  the  arc. 

Examining  this  switch  you  will  notice  that  when  it  is 
to  the  right  its  lower  blade  short  circuits  the  resistance  im- 
mediately below  it.  This  resistance  is  in  two  units,  the  same 
being  in  multiple  with  each  other,  and  the  negative  arma- 
ture wire  from  the  generator  is  connected  to  its  center.  By 
this  arrangement  the  current  going  through  either  one  of 
the  arcs  enters  the  outside  terminals  of  the  resis'tance  units 


FOR    MANAGERS    AND    OPERATORS 


427 


and  travels  through  them  back  to  the  negative  pole  of  the 
generator.  This  resistance  offers  a  drop  of  about  5  volts 
when  the  two  resistances  are  in  parallel  with  each  other  and 
in  series  with  the  arc,  and  it  is  in  some  instances  found 


//O  VOLT  off 


Plate  7,  Figure  212. 

desirable  to  leave  the  resistance  in  circuit.  For  highest 
efficiency,  however,  there  can  be  furnished  an  extra  switch 
blade,  by  means  of  which  the  resistance  unit  can  be  entirely 
short  circuited  when  the  three-pole  switch  is  to  the  right 
for  single  lamp  operation.  When  the  lower  three-pole  switch 


428  MOTION    PICTURE   HANDBOOK 

is  to  the  left  the  compound  windings  on  the  generator  are 
reversed  and  act  with  the  shunt  field,  which  makes  the 
generator  a  cumulative  compound  machine,  under  which  con- 
dition it  produces  constant  potential.  When  the  lower  three- 
pole  switch  is  to  the  left  the  short  circuit  across  the  resis- 
tance unit  is  open  and  the  resistance  is  now  connected  so 
that  the  left-hand  half  is  in  series  with  one  of  the  arcs  and 
the  right-hand  in  series  with  the  other  arc.  The  upper  three- 
pole,  double-throw  switch  is  to  the  right  when  the  generator 
is  working,  but  should  the  generator  break  down  it  is  only 
necessary  to  throw  it  over  to  the  left  to  cut  in  alternating 
current  at  the  arc  through  the  economizers. 

A-A,  P.  7,  Fig.  212,  are  ammeters,  one  for  each  arc,  and  V 
the  voltmeter.  At  the  top  on  P.  7,  it  will  be  observed  that 
arc  No.  2  takes  current  through  a  double-pole,  double-throw 
switch.  This  arrangement  is  offered  as  a  suggestion  where 
in  some  instances  it  is  necessary  to  take  extra  precaution  in 
order  always,  under  all  conditions,  to  maintain  one  of  the 
arcs.  For  instance,  in  some  theatres  where  the  entire  pro- 
jection installation  is  supplied  from  the  electric  company's 
two  or  three  phase  service  the  house  lighting  may  be  on  an 
entirely  separate  set  of  mains,  with  separate  transformer 
and  meter  on  single  phase.  The  house  lighting  system  may 
be  fed  from  another  street,  one  or  more  blocks  away.  In  a 
case  of  this  kind  the  second  emergency  connection  from  the 
single  phase  or  house  lighting  service  may  be  brought  into 
one  of  the  machine  switches  through  suitable  means  of  vol- 
tage reduction,  by  the  use  of  one  of  the  sets  of  terminals  on 
the  double-throw,  double-pole  switch.  In  P.  7,  the  lower 
three-pole,  double-throw  switch  is  to  the  right  for  one  lamp, 
and  to  the  left  when  two  lamps  are  being  operated. 

Mercury  Arc  Rectifier 

General  Remarks 

THE  mercury  arc  rectifier  is  a  device  marketed  by  two 
manufacturers,  the  General  Electric  Company  and  the 
Westinghouse  Electric  and  Manufacturing  Company, 
for  the  purpose  of  changing  alternating  current  of  standard 
line  voltage  to  direct  current  at  arc  voltage,  the  reduction  in 
pressure  being  accomplished  by  means' of  an  auto  transformer 
which  is  an  integral  part  of  the  machine. 

In  describing  the  "Principle  of  Operation,"  let  it  be  clearly 
understood    that    I    have    sacrificed    accurate    correctness    in 


FOR    MANAGERS    AND    OPERATORS  429 

favor  of  "understandableness."  To  tell  exactly  what  happens 
inside  of  a  rectifier  tube  would  be  a  good  deal  like  trying  to 
explain  what  electricity  is  or  to  explain  the  reason  for  the 
force  of  gravity.  Electrical  engineers  acquainted  with  the 
mercury  arc  rectifier  have  various  opinions  as  to  exactly 
what  takes  place  inside  the  tube,  and  while  I  have  every 
respect  for  the  opinion  of  these  eminent  gentlemen  I  am  ad- 
vancing a  theory  which,  while  it  may  be  entirely  wrong, 
sounds  to  me  like  common  sense.  In  fact  I  wrote  it  with 
two  ends  in  view,  viz.:  first,  to  make  the  matter  understand- 
able to  the  ordinary  operator;  second,  to  set  forth  my  view 
of  what  ought  to  take  place,  simply  viewing  the  matter  in 
the  light  of  common  sense.  With  this  explanation  the  fol- 
lowing is  submitted: 

Principle  of  Operation. — The  mercury  arc  rectifier  consists 
essentially  of   a   sealed- glass  bulb,   from  which   the   air  has 


Figure  213. 

been  exhausted,  provided  with  four  terminals,  A,  Al,  B  and  C, 
Fig.  213.  Within  this  tube  is  a  quantity  of  mercury  the 
purpose  of  which  will  be  explained  further  on.  The  two 
upper  terminals  A,  Al,  Fig.  213,  are  of  graphite  or  other 
suitable  material,  and  the  two  lower  ones  B,  C,  Fig.  213, 
are  of  mercury,  the  smaller  one  of  the  two,  C,  Fig.  213,  being 


430  MOTION    PICTURE   HANDBOOK 

what  is  known  as  a  "starting  terminal."  When  the  bulb  is  in 
a  vertical  position  the', pools  of  mercury  in  terminals  B  and  C 
are  separated,  but  when  the  tube  is  tilted  or  rocked  sidewise 
(to  the  left)  these  mercury  pools  are  brought  temporarily  into 
contact  with  each  other  for  the  purpose  of  starting  the  tube 
into  action. 

The  vacuum  bulb,  in  its  active  state,  contains  vapor  of 
mercury,  which  is  a  conductor  of  electricity  only  under  cer- 
tain conditions.  Current  will  readily  pass  from  either  one 
of  the  graphite  terminals,  A,  Al,  Fig.  213,  into  the  mercury 
vapor,  and,  with  the  circuit  completed  by  the  arc,  will  pass 
from  it  into  mercury  terminal  B,  and  thus  on  through  the 
arc. 

Alternating  current,  however,  changes  its  direction  many 
times  in  the  course  of  a  second  of  time,  but  when  the  direc- 
tion of  flow  seeks  to  reverse  itself  and  pass  from  the  mercury 
to  the  graphite  terminals,  these  terminals  offer  resistance 
which  prevents  the  flow,  and  thus  the  graphite  terminals 
act  as  check  valves,  permitting  the  current  to  pass  into  mercury 
vapor,  but  preventing  it  from  passing  into  the  graphite  terminals. 

The  alternating  current  supply  circuit  is  connected  to 
graphite  terminals  A,  Al,  Fig.  213,  through  an  auto-trans- 
former which  lowers  the  voltage  to  that  required  at  the  arc, 
and  as  the  action  is  such  as  will  only  allow  current  to  flow 
in  one  direction,  the  pulsations  of  current  which  pass  alter- 
nately/ from  terminal  A  and  Al,  Fig.  213,  into  'the  mercury 
vapor  must,  of  necessity,  pass  out  of  the  vapor  through 
mercury  terminal  B,  Fig.  213,  which  is  connected  to  the 
arc  lamp,  and  thus  we  have  a  continuous,  slightly  pulsating 
current  delivered  at  the  arc.  The  pulsations  would  ordinarily 
be  quite  pronounced  on  the  D.  C.  side,  but  this  matter  is 
taken  care  of  by  a  feature  of  the  auto-transformer  (an 
integral  part  of  the  machine)  which  serves  to  "flatten  out" 
or  decrease  the  natural  pulsations,  so  that  the  current  deliv- 
ered at  the  arc  has  a  very  nearly  constant  potential  value. 

Before  the  bulb  starts1  to  rectify,  the  mercury  vapor  is 
absent,  and,  between  electrodes  A,  Al,  B,  and  C  there  is  a 
vacuum  which  presents  high  resistance,  and  this  space  must 
be  filled  with  mercury  vapor  before  current  can  pass.  Once 
this  has  been  accomplished,  however,  and  current  flow  has 
started,  it  will  continue  to  flow  as  long  as  the  supply  is 
uninterrupted.  Any  interruption  of  the  supply,  however, 
even  for  the  shortest  period  of  time,  permits  the  vacuum 
to  re-establish  itself  and  stops  the  operation  of  the  bulb. 


FOR    MANAGERS    AND    OPERATORS  431 

In  order  to  establish  the  mercury  vapor,  or  conducting 
medium,  the  bulb  is  tilted  so  that  the  space  between  the 
large  and  small  mercury  pools  in  terminals  B,  C,  is  tem- 
porarily bridged  by  mercury,  whereupon  current  passes  be- 
tween terminals  B  and  C  through  a  special  circuit  provided, 
directly  from  the  A.  C.  supply  lines.  As  the  tube  rocks  back  to 
upright  position  this  little  mercury  bridge  between  terminals 
B  and  C  is  broken,  and  in  breaking  it  forms  an  arc  or  spark, 
and  it  is  this  arc  or  spark  which  creates  the  initial  current 
carrying  mercury  vapor  and  puts  the  tube  into  operation. 
Once  operation  is  started  the  rectifier  will  continue  to  operate 
indefinitely  as  long  as  the  current  supply  is  uninterrupted. 

The  alternating  current  supply  c:rcuit  is  connected  to  an 
auto-transformer1  or  main  reactance,  the  terminals  of  which 
are  connected  to  the  terminals  A,  Al,  Fig.  213.  From  ter- 
minal B  the  current  passes  through  the  arc  and  the  circuit 
is  completed  through  a  connection  to  the  middle  point  of 
the  auto-transformer. 

In  the  main,  rectifiers  consist  of:  (A)  an  auto-transformer; 
(B)  a  regulating  reactance  coil;  (C)  a  tilting  mechanism; 
(D)  a  relay;  (E)  a  dial  switch;  (F)  a  switch  or  other  means 
for  connecting  the  auto-transformer  directly  to  the  arc,  and, 
(G)  a  bulb  and  its  holder. 

The  reactance  coil  is  for  the  purpose  of  giving  steadiness 
to  the  arc  and  limiting  the  current  when  the  carbons  are 
brought  together  when  striking  an  arc  (a  dead  short  circuit) 
to  a  value  which  will  not  be  injurious  to  the  bulb. 

Modern  rectifiers  are  so  equipped  that  in  case  the  bulb  gives 
out  the  operator  can  swatch  over  to  the  auto-transformer  and 
continue  the  show  with  alternating  current,  using  the  auto- 
transformer  as  an  economizer.  Also  modern  rectifiers  are 
equipped  with  a  dial  switch  by  means  of  which  the  operator 
can  instantly  vary  the  amperage  within  certain  limits. 

Installation. — Rectifiers  are  ordinarily  received  in  two 
separate  shipments,  one  of  which,  the  rectifier  itself,  weighing 
several  hundred  pounds,  will  probably  come  by  freight.  The 
other,  the  glass  bulb,  is  carefully  packed  in  a  specially  made 
case,  and  is  usually  sent  by  express.  In  removing  the  bulb 
from  its  crate  proceed  strictly  according  to  directions  in 
loosening  the  crate,  after  which  carefully  lift  out  the  bulb. 
It  will  be  in  an  inverted  position.  Turn  it  slowly  over  and 
carefully  let  the  mercury  run  down  into  terminals  B,  C.  In 
rolling  the  mercury  should  make  a  sharp,  cracking  sound, 
which  is  an  indication  that  the  tube  is  in  good  condition. 


432  MOTION    PICTURE   HANDBOOK 

The  rectifier  should  not  be  located  directly  in  the  operat- 
ing room  unless  there  be  some  means  provided  for  covering 
the  bulb  so  that  its  light  will  not  shine  in  the  room.  Light 
in  the  operating  room  is  highly  objectionable.  One  very 
good  method  is  to  install  the  rectifier  in  an  adjoining  room 
and  cut  a  space  through  the  wall  just  large  enough  to  admit 
the  front  panel  of  the  rectifier.  This  allows  the  operator  to 
have  access  to  the  switches  for  the  purpose  of  varying  the 
amperage,  or  changing  over  to  A.  C.,  and  at  the  same  time 
excluding  the  light  from  the  room. 

Some  managers  place  the  rectifier  in  such  position  that  it 
can  be  seen  from  the  front  of  the  theatre  where  the  weird 
greenish  light  given  off  by  the  bulb  attracts  considerable 
attention.  As  a  general  proposition,  however,  the  modern 
rectifier  which  allows  of  changing  amperage  by  means  of  a 
switch  should  be  so  located  that  the  operator  can  reach 
these  switches  without  leaving  the  operating  room. 

There  is  no  vibration  and  no  noise  except  a  humming 
sound  which  emanates  from  the  transformer.  Care  should 
be  exercised  that  there  is  no  sheet  metal  near  the  machine, 
sincei  if  there  is  the  transformer  would  probably  set  up 
vibration  therein  and  thus  create  more  or  less  objectionable 
noise. 

Comparative  Results. — Experiments  made  by  Simon  Henry 
Gage  and  Henry  Phelps  Gage,  Cornell  University,  have 
shown  that  the  losses  through  the  pulsation  of  the  current 
with  the  mercury  arc  rectifier  are  but  very  slight.  A  mer- 
cury arc  rectifier  using  40  amperes  at  52  volts  gave  12,150 
C.  P.,  whereas  straight  D.  C.,  40  amperes  at  51  volts,  with 
the  same  carbon  set  only  gave  12,350  C.  P.,  a  difference  of 
about  200  C.  P. 

Tubes  should  never,  under  any  circumstances,  be  operated 
above  their  maximum  capacity. 

On  the  following  page  appears  a  chart  indicating  the 
various  troubles  one  is  likely  to  encounter  when  operating 
a  rectifier,  together  with  the  most  probable  cause  or  causes 
of  each.  A  careful  study  of  this  diagram  ought  to  be  of 
much  value  to  users  of  rectifiers.  With  this  chart  and  fche  de- 
tailed instructions  contained  in  this  book,  plus  a  fair  supply 
of  "horse  sense,"  I  believe  any  operator  ought  to  handle  a 
rectifier  without  any  serious  difficulty. 


FOR    MANAGERS    AND    OPERATORS 


433 


r>3 

'*  r 

/•Current   at  switch  —  Fuses  blown. 

B 

J  \  No    current 

at    tube 

E 

S  1            terminals. 

c 

u  ^ 

l.No  current  at  switch  —  Line  voltage 

oft. 

2 

g 

'Friction    or  bent    stud. 

EH 

PJ 

3 

CO   I 

H  1 

Relay    contact    is   poor. 

f! 

£ 

§^  Relay  contact  not  closed.  j  Tilting  clrcuit  open 

I 

<M 

•a 

§ 

«l 
B{ 

Secondary    coil     of     magnet     short- 
circuited. 

M" 

CO  . 

EH  L 

*• 

H 
O 

bo 

Q 

H 

"3 

0} 

criJ  Amalgam    bridge    between    electrodes  —  'Install    new    tube. 
S  *• 

P 

* 

EH 

£ 

EH 

CO 

Hf 

W 

TLamp  circuit  open. 

53 

P  -|  D.  O.  circuit  open.  -I 

• 

^                                           Carbons    not    making     good    contact    with 

.1 

I 

L         each  other  or  with  the  lamp  Jaws. 

'Lead  on  starting  anode  broken  or  loose. 

OJ 

EH 

Does    not    return, 
to  vertical. 

Mercury     pools     do     not    make  f 
contact.                                          Adjust     tube; 
-j          does    not 

it 

tilt 

p 

far  enoug 

ti. 

EH 

^Friction  In   tube  holder. 

H" 

Returns  to  vertical 

with-  rTube  is  defective.                      r 

P 
EH 

out    flash    after    re-J                                                         I  New  tube> 
peated  tilts.                  LTube   has   lost   its   vacuum.  L 

Flashes    and    goes    out.JLead   broke?"™   electr°de   an°de    1OOSe   °r 

Tube     continues     to    tilt  !  Relay   does  not  open!  Winding  short-circuited, 
after  starting.  the  circuit.  friction  or  bent  stud. 


Tube  goes  out. 


Lamp   carbons  separated   too   far. 


(-Voltage   of  circuit   low. 
\  Frequency  of  current  not   right 

Tube       tilts       feebly. -i  Friction  in  tilting  mechanism. 
LTube  is  too  heavy  at  bottom. 
'Reactance  coll  loo'se  on  frame. 
Reactance  coil  air  gap  not  wedged  tight. 
Outfit  Is  noisy.  -{ Cover   vibrates. 

Operating  room    floor    vibrates — set   outflt    on    felt 
pads. 


Arc  Is  noisy. 


Carbons    too  'hard — use   softer   ones. 


NOTE. — When  proper  vacuum  exists  the  mercury  gives  off  a  sharp 
clicking  sound  when  It  is  run  from  one  end  of  the  tube  to  the  other. 
Absence  of  this  sound  and  the  presence  of  air  bubbles  show  loss  of 
vacuum. 

Tube  may  be  defective  by  short-circuiting  between  starting  anod* 
and  cathode.  When  in  this  condition  it  is  badly  blackened, 


434  MOTION    PICTURE   HANDBOOK 

GENERAL  ELECTRIC  MERCURY  ARC   RECTIFIER 

The  General  Electric  Company,  Schenectady,  N.  Y.,  manu- 
factures rectifiers  for  use  on  projection  circuits  in  three 
capacities,  30,  40  and  SO  amperes.  The  General  Electric 


Ammeter 


AdaptinqiinHs  for 
//OarncfZZOVo/t  supply 
Connect  as  shown  on. 

ZZOandasper 
dotted  ftnes  for  I/O 


High 


Fuses 


Switch  forus/ng 
either  A.C,  or 
D.C.attheArc  . 


Low 

ffequ/at/ng?  Dial 
'      Switch    • 


Ma/n  Reactance 


Plate  1,  Figure  214. 

rectifiers  may  all  be  used  on  either  110  or  220  volts.     They 
are  made  for  50  to  133  cycle  circuits,  and  for  25  to  40  cycle 

circuits.    The  machines  are  of  the  panel  or  switchboard  type 


FOR  MANAGERS  AND  OPERATORS 


435 


in  that  the  front  of  the  machine  consists  of  a  slate  switch- 
board \l/2  inches  thick  and  16  by  24  inches  in  size,  finished 
in  dull  black  and  mounted  above  the  main  reactance,  as  per 
PJate  1.  On  the  front  of  this  board  are  mounted  the  fuses, 
a  three-pole,  double-throw  switch,  the  adapting  links,  the 
dial  switch,  and  the  ammeter  and  voltmeter,  one  or  both, 
provided  they  are  ordered;  ammeters  and  voltmeters  only 


Tube—*- 


Clip 
rfnoofe 


Shafting  Cot/ 

Starting  Anode 
ffe/ay 

D.C.  Terminate 

5er/es  underload 
Relay 

Current  Limiting 
Resistance 


Current  Limiting 
Potential  Relay 


Regulating 
Reactance 


Mam 


Reactance 


Plate  2,  Figure  215. 

being  sent  when  specially  ordered.  On  the  back  of  the 
board  or  panel  are  mounted  the  regulating  reactance,  the 
various  relays,  current  limiting  resistances,  tube,  etc.,  as  in 
Plate  2.  The  general  appearance  of  the  machine  is  pleasing 
to  the  eye.  It  is  not  excessive  in  weight,  and  occupies  but 
little  floor  space.  The  G.  E.  rectifiers  are  entirely  automatic 
in  their  operation.  All  that  is  necessary  to  start  the  rectifier 
is  to  close  the  A.  C.  supply  and  machine  table  switches  and 


436  MOTION    PICTURE   HANDBOOK 

bring  the  carbons  in  the  lamp  together,  whereupon  the  recti- 
fier automatically  will  begin  business.  The  size  of  rectifiers 
to  be  used  depends  upon:  (a)  area  of  screen  surface  to  be 
illuminated;  (b)  character  of  screen  surface;  (c)  the  amount 
of  light  there  is  in  the  auditorium.  (See  Amperage,  Page 
157.) 

The  Instruments  (when  ordered)  are  of  the  D'Arsonval 
or  permanent  magnet  type.  When  both  ammeter  and  volt- 
meter are  supplied  the  two  are  mounted  together  in  one 
case,  and  the  whole  placed  on  a  bracket  above  the  panel. 
The  instruments  are  accurate  and  are  connected  in  the  sec- 
ondary, or  D.  C.  side,  hence  show  the  voltage  and  amperage 
at  the  arc.  They  always  should  be  ordered  when  a  rectifier  is 
purchased.  I  myself  would  prefer  that  they  be  mounted  on 
the  wall  in  front  of  the  operator,  rather  than  on  the  rectifier, 
which  may  not  be  placed  directly  under  the  operator's  eye, 
and  these  instruments  may  be  removed  from  the  rectifier 
and  so  mounted  if  desired. 

Fuses. — Fuses  of  greater  capacity  than  those  furnished  with 
the  rectifier  should  never  be  used.  For  a  30  ampere  rectifier 
use  35  ampere  fuses;  for  40  or  50  ampere  machine  use  55 
ampere  fuses. 

From  Direct  Current  to  Alternating  Current. — In  Plate  1 
we  see  a  triple-pole,  double  throw  switch  in  the  center  of 
the  panel.  This  switch  is  for  the  purpose  of  immediately 
changing  from  D.  C.  to  A.  C.,  using  the  main  reactance 
as  an  economizer  in  case  anything  should  happen  to  the 
tube,  or  in  case  it  should  be,  for  any  reason,  necessary  to  use 
A.  C.  at  the  arc.  The  switch  as  shown  in  Plate  1  is  set 
for  D.  C.;  by  throwing  it  over,  downward,  the  D.  C.  rectifica- 
tion is  stopped  and  alternating  current  is  supplied  at  the 
arc.  If  the  switch  is  thrown  over  to  A.  C.  it  may  be  found 
that  the  alternating  current  is  too  low,  in  which  case  lead  3, 
Plate  3,  may  be  moved  along  studs  1,  Plate  3,  until 
the  right  current  is  obtained.  Do  not  use  over  60  amperes.  It 
should  be  borne  in  mind  that  the  rectifier  is  built  primarily  for 
changing  A-  C.  to  D.  C.,  and,  while  its  main  reactance  may  be 
used  as  an  economizer  and  provision  is  made  for  that  purpose, 
that  provision  is  only  designed  for  emergency.  The  machine 
should,  so  far  as  possible,  be  used  exclusively  as  a  rectifier. 

Connecting  or  Adapting  Links,  Plate  1,  are  for  the  purpose 
of  adapting  the  rectifier  to  either  110  or  220  volt  supply.  In 
order  to  change  from  one  to  the  other  all  that  is  necessary 
is  to  change  the  links  as  indicated  in  Plate  1.  For  220  volt 


FOR  MANAGERS  AND  OPERATORS 


437 


current  they  should  be  connected  to  the  upper  stud  and  the 
two  outer  lower  studs;  for  110  volt  current  they  should  be 
connected  to  the  two  upper  and  the  two  inside  lower  studs. 

The  Dial  Switch  has  eleven  contacts,  Plate  1,  which  are 
connected  to  eleven  taps  on  the  regulating  reactance,  Plates  3 
and  5.  This  connection  is  clearly  shown  in  Plate  3,  in  which  the 
regulating  reactance,  2,  has  been  (dropped!  down  to  show 
the  connections.  This  switch  is  for  the  purpose  of  regulat- 
ing the  amperage  at  the  arc,  and  any  amperage  within  the 
capacity  of  thes  rectifier  may  be  instantly  had  by  merely 
moving  the  switch  to  the  left  to  raise  and  to  the  right  to 
lower,  as  per  Plate  1. 

The  Main  Reactance,  Plate  1,  is  nothing  more  or  less 
than  a  very  well  constructed  auto-transformer,  the  insula- 
tion of  which  is  calculated  to  withstand  many  times  the 
normal  operating  voltage.  These  reactances  are  given  the 
vacuum  compound  treatment,  which  is  the  best  known  re- 
sister  to  moisture,  as  well  as  a  high  class  preservative.  The 
main  reactance  has  three  distinct  functions:  (a)  It  adjusts 
the  voltage  of  the  alternating  current  to  the  proper  value  to 
apply  to  the  anodes  of  the  tube  to  secure  the  proper  D.  C. 
voltage  at  the  lamp ;  (b)  it  supplies  a  neutral  point  between  the 
alternating  current  lines  and  forms  the  negative  of  the  direct 
current  lines;  (c)  by  its  reactance  it  keeps  the  rectifier  tube 
in  operation  while  the 
current  passes  through 
the  zero  point  of  the 
alternating  current 
wave. 

The  Regulating  Re- 
actance.— The  regulat- 
ing reactance,  Plates  2 
and  3,  is  nothing  more 
or  less  than  a  choke 
coil  with  eleven  or 
more  taps  taken  off  at 
certain  points  along 
the  winding,  these  taps 
being  connected  to  an 
equal  number  of  con- 
tacts or  studs  of  the 
dial  switch,  P.  1  and  3, 

so  that  the  alternating  current  can  be  choked  back  or  reduced 
to  a  value  just  sufficient  to  give  the  desired  amperage  at  the 
arc.  It  produces  practically  the  same  effect  as  would  a  rheo- 
stat, but  with  far  less  waste  of  power.  By  manipulating  the 


Plate  3,  Figure  216. 


438 


MOTION    PICTURE    HANDBOOK 


dial  switch  any  D.  C.  amperage  within  the  range  of  the 
rectifier  is  made  instantly  available. 

The  Tubes. — The  rectifier  tube  has  already  been  described 
under  "General  Remarks,"  and  the  General  Electric  tube  is 
shown  in  Plate  2  and  Fig.  213. 

Tubes  should  be  handled  with  care,  and  in  uncrating  a  new 
tube  the  instructions  which  come  with  it  should  be  closely  and 


Plate  4,  Figure  217. 

carefully  followed.     See  General   Remarks,  under   caption  "In- 
stallation," Page  431. 

Plate  4  shows  a  rough  diagram  of  the  connections  of  the  Gen- 
eral Electric  mercury  arc  rectifier;  all  parts  of  the  rectifier  are 
shown  diagrammatically  without  reference  to  their  actual  position 
with  relation  to  one  another  when  mounted  on  the  rectifier,  the 
idea  being  merely  to  illustrate  the  method  employed  in  starting. 


FOR    MANAGERS    AND    OPERATORS  439 

By  referring  to  Plate  4  it  will  be  seen  that  three  coils  are  used  for 
starting,  viz:  a  shaking  magnet,  a  series  overload  relay,  and  a 
starting  anode  relay,  the  latter,  which  is  normally  open,  but  picks 
up  when  the  carbons  of  the  lamp  are  brought  together,  thus  clos- 
ing the  shaking  magnet  circuit,  see  D,  Plate  4,  whereupon  the 
shaking  magnet  pulls  the  tube  over  to  one  side,  or,  in  other 
words,  "rocks"  it,  thus  allowing  the  mercury  in  cathode  B, 
Fig.  213,  to  bridge  over  and  form  a  connection  with  the  mer- 
cury in  starting  anode  C,  which  shunts  the  current  from 
the  starting  anode  relay  D,  Plate  4,  circuit,  and  operates  to 
demagnetize  its  coil,  thus  allowing  its  plunger  to  fall  and 
open  the  shaking  magnet  circuit,  whereupon  the  tube,  by  its 
own  weight,  rocks  back  into  vertical  position,  thus  breaking 
the  mercury  bridge  between  anode  C  and  cathode  B,  Fig. 
213.  After  the  tube  has  started  operating,  and  the  arc  has 
been  struck,  the  series  underload  relay,  which  is  connected 
in  the  D.  C.  circuit,  picks  up,  thus  cutting  the  starting  anode 
relay  and  shaking  magnet  entirely  out  of  circuit.  If  the  tube 
does  not  start  ,at  once  the  shaking  magnet  continues  to  rock 
the  tube  until  it  does. 

Installation. — After  the  rectifier  set  has  been  uncrated  and 
placed  in  its  operating  location  (See  "Installation,"  Page 
431),  the  tube  should  be  placed  in  the  holders  E,  F,  as  per 
Plate  2.  This  is  accomplished  by  pressing  the  narrow  part 
of  the  tube,  just  above  anode  arms  A,  Al,  into  upper  clip  E, 
Plate  2,  carefully  lowering  the  tube  until  anodes  A,  Al,  rest 
on  the 'lower  clips,  F,  Plate  2.  Having  got  the  tube  in  place, 
you  will  find  four  wires  covered  with  a  sort  of  glass  bead 
insulation,  these  wires  terminating,  in.  brass  spring  clips, 
Plate  5.  Connect  the  two  upper  ones  (either  one  to  either 
anode)  to  anodes  A,  Al,;  the  small  lower  one  to  starting 
anode  C,  Fig.  213,  and  the  large  lower  one  to  cathode  B, 
Fig.  213,  as  shown  in  Plate  2.  Next  connect  the  A.  C.  supply 
lines  to  the  two  terminals  (marked  A-C)  at  the  upper  left 
hand  corner  of  the  panel — that  is  to  say,  the  left  hand  corner 
as  you  stand  facing  the  tube  on  the  back  side  of  the  machine. 

These  terminals  are  shown  on  Plate  5.  Next  connect  the 
positive  D.  C.  terminal,  Plate  2,  marked  -j-  to  one  side  of 
the  machine  table  switch,  and  through  the  machine  table 
switch  to  the  upper  carbon  arm  of  the  lamp,  and  connect 
the  negative  (marked  — )  D.  C.  terminal  to  the  other  side  of  the 
machine  table  switch,  and  through  it  to  the  lower  carbon  arm 
of  the  lamp.  The  ^D1.  C.  terminals  will  be  seen,  properly 
labeled  in  Plate  2.  Connect  the  adapting  links  in  the  front 


440  MOTION    PICTURE   HANDBOOK 

of  the  panel  according  to  the  voltage  of  your  alternating 
current  supply,  as  per  Plate  1.  Having  accomplished  all  this, 
with  the  triple-pole  switch  closed  in  the  upper  position,  as  per 
Plate  1,  and  with  the  A.  C.  supply  and  D.  C.  machine  table 
switch  closed,  the  rectifier  is  ready  to  start. 

Operation. — To  start  the  rectifier  bring  the  lamp  carbons 
together,  whereupon  the  tube  will  rock,  and  usually  start  at 
once.  As  soon  as  it  starts  slowly  separate  the  carbons  to 
the  usual  distance  when  using  D.  C,  say  approximately  one- 
fourth  of  an  inch  for  ordinary  amperage.  When  the  carbons 
have  been  separated  far  enough  that  the  voltage  between 
them  is  about  45,  the  potential  relay,  4,  Plate  5,  (if  it  is  a 
40  or  50  ampere  rectifier;  there  is  none  on  the  smaller  size) 
will  operate  and  short-circuit  the  current  limiting  resistance, 
3,  Plate  5,  thus  increasing  the  arc  current  to  Whatever  value 
the  dial  switch  is  set  for. 

Caution. — When  you  first  begin  to  use  a  rectifier  be  sure 
that  the  potential  relay  operates.  If  it  does  not  the  current 
limiting  resistance,  3,  Plate  5,  will  heat,  and  whereas  it 
would  be  difficult  to  actually  burn  it  out  still  damage  might 
be  done  to  the  insulation  of  the  surrounding  wires. 

The  operator  can  tell  when  this  relay  acts  as  follows: 
When  the  carbons  are  first  separated  the  current  will  be 
comparatively  weak,  and  when  the  relay  acts  there  will  be 
a  sudden  increase  in  brilliancy  at  the  spot.  The  knack  of 
detecting  the  action  of  the  relay  can  be  acquired  by  starting 
the  arc  several  times  and  slowly  separating  the  carbons 
until  the  relay  picks  up.  In  doing  this  it  would  be  well  to 
have  a  man  by  the  rectifier  to  tell  you  when  it  does  pick  up, 
if  the  rectifier  is  at  a  distance.  Half  a  dozen  trials  ought 
to  show  just  how  the  thing  works,  so  that  you  will  have  no 
further  trouble  in  detecting  its  action.  To  stop  the  rectifier, 
open  either  the  A.  C.  or  D.  C.  switch  or  the  triple-pole 
switch. 

Operating  Two  Arcs  from  One  Rectifier. — When  it  is  desir- 
able to  operate  two  arcs  from  one  rectifier  the  General 
Electric  Company  will  furnish  two  resistances  equipped  with 
contactors,  one  to  be  used  in  series  with  each  lamp.  These 
resistances  consist  of  a  number  of  coils,  inclosed  in  a  venti- 
lated sheet  metal  box,  for  mounting  on  the  frame  of  the 
machine,  or  standing  on  the  floor  beside  the  machine.  Dia- 
gram, Plate  6,  shows  the  resistances  connected  in  the  lamp 
circuits.  The  operation  of  fading  one  reel  into  another  is 
briefly  as  follows:  Assume  the  operator  to  be  running  a 


FOR    MANAGERS    AND    OPERATORS  441 


Plate  5,  Figure  218. 


442 


MOTION    PICTURE    HANDBOOK 


Rectifier  Terminals 


Arc  No.2  X 


Resistance 


Contactor 


Plate  6,  Figure  219. 


picture  machine  on  No.  1,  in  which  case  the  contactor  is 
closed  by  hand  (cutting  out  the  resistance  which  is  normally 

in  circuit)  at  the  start 
and  held  in  this  posi- 
tion by  a  magnet  coil. 
At  any  time  while  this 
reel  is  running  the 
operator  (leaving  the 
contactor  on  arc  No. 
2  open)  may  start  ma- 
chine No.  2  at  about  10 
amperes,  thus  allowing 
the  carbon  to  be  warm- 
ed up  on  No.  2,  while 
the  reel  is  still  being 
run  on  machine  No.  1. 
At  the  end  of  the  reel 
on  machine  No.  1,  ma- 
chine No.  2,  with  arc 

burning  with  resistance  in  circuit,  is  then  started;  the  con- 
tactor is  closed,  thus  cutting  out  the  resistance  and  boost- 
ing the  current  to  normal,  at  the  same  time  short-circuiting 
the  arc  of  machine  No.  1,  putting  it  out,  which  stops  the  cur- 
rent flowing  in  resistance  box  No.  1,  thus  opening  the  con- 
tactor. The  resistance  cannot  be  accidentally  left  out  when 
the  second  arc  is  struck.  W'hen  the  first  arc  is  short-circuited 
the  contactor  opens,  which  automatically  cuts  in  the  resistance. 
These  resistances  prevent  overloading  the  rectifier.  Remember 
that  the  resistance  is  in  when  the  contactor  is  open. 

I  would  recommend  to  managers  the  purchase  of  one  of 
the  larger  rectifiers.  The  modern  tendency  is  to  use  high 
amperage  and  project  a  brilliant  picture.  The  first  cost  will 
be  greater,  but  it  is  worth  the  money.  This,  however,  may  be 
qualified  by  saying  that  in  very  small  towns  where  the  pos- 
sible patronage  is  limited  and  every  penny  of  expenditure 
has  to  be  closely  scrutinized  it  might  not  be  advisable  to  go 
above  the  30  ampere  size. 

Explanations. — We  have  told  you  in  a  general  way  of  the 
action  of  the  rectifier.  Now  let  us  examine  into  its  "chronom- 
eter balance  and  cylinder  escapement"  and  see  if  we  can 
find  out  what  it's  all  about. 

Note:  You  need  not  be  afraid  to  perform  any  of  these  va- 
rious operations  in  case  of  necessity;  just  follow  the  directions 
and  use  a  little  common  sense,  remembering  where  each  part  goes, 


FOR    MANAGERS    AND    OPERATORS  443 


Plate  7,  Figure  220. 


444  MOTION    PICTURE   HANDBOOK 

or,  if  necessary,  attaching  a  labeled  tag  to  it  as  you  remove  it. 
There  is  no  mystery  about  these  things.  All  too  often  the  opera- 
tor hesitates  to  attempt  the  making  of  repairs  through  fear  of 
being  unable  to  get  the  thing  back  into  shape.  The  rectifier 
is  strongly  made,  and  its  parts  are  very  simple.  I  repeat: 
Follow  the  instructions  here  given,  supplementing  them  by 
ordinary  common  sense,  and  you  will  be  extremely  unlikely 
to  have  any  trouble. 

The  current-limiting  resistance  3,  Plate  5,  consists  of  a 
strip  of  resistance  metal,  wound  in  spiral  form,  covered  with 
insulating  material  and  supplied  with  contacts  at  either  end. 
Resistances  1  and  9,  Plate  5,  are  made  of  wire  wound  on 
asbestos,  and  the  whole  dipped  in  an  insulating  material. 

The  purpose  of  current-limiting  resistance  3,  Plate  5,  is  as 
follows:  When  the  carbons  are  brought  together  the  effect 
is,  to  all  intents  and  purposes,  to  form  a  short  circuit,  which 
would  have  the  effect  of  sending  a  heavy  rush  of  current 
through  the  arc  circuit.  Resistance  3  in  effect  takes  the 
place  of  the  resistance  offered  by  the  arc  after  the  carbons 
are  separated.  This  resistance  is  automatically  cut  into  cir- 
cuit when  the  plunger  of  relay  4,  Plate  5,  is  down;  or,  in 
other  words,  when  relay  4  is  "open."  When  the  carbons  are 
opened  and  the  arc  struck  the  effect  is  to  add  the  resistance 
of  the  arc  to  the  resistance  offered  by  current-limiting  resist- 
ance, 3,  and  thus  raise  the  voltage  of  the  lamp  circuit.  When 
this  voltage  reaches,  a  certain  point  (about  40  volts)  the 
energy  of  the  magnet  of  relay  4  becomes  sufficient  to  raise 
plunger  5,  Plates  5  and  7,  and  bring  blade  6,  Plates  5  and  7, 
into  contact  with  block  7,  Plates  5  and  7,  thus  short-circuit- 
ing current-limiting  resistance  3,  and  raising  the  D.  C.  am- 
perage. 

Should  relay  4  at  any  time  fail  to  act  it  is  most  likely  that 
plunger  5,  Plates  5  and  7,  is  stuck,  which  might  be  caused 
by  a  grain  of  dirt  or  from  some  other  cause.  This  plunger 
may  be  removed  from  the  magnet  by  pulling  out  split  key 
18,  Plates  5  and  7,  and,  holding  stationary  nut  9  at  the  top 
of  the  plunger,  unscrew  plunger  5  by  turning  its  lower  end. 
Having  removed  the  plunger  and  ascertained  the  cause  of  its 
sticking,  it  may  be  replaced,  and  when  you  are  able  to  get 
split  key  18  into  its  hole  you  may  know  that  the  plunger  is 
in  the  proper  location.  In  replacing  nut  be  sure  to  get  it  right 
side  up.  If  you  can't  get  the  split  key  in  ihe  chances  are  that 
you  haven't  the  nut  right  side  up.  Also,  in  replacing  nut  9,  be 
sure  to  get  the  two  washers  underneath  it  in  place. 


FOR    MANAGERS    AND    OPERATORS  445 

It  will  be  well  to  clean  the  contact  between  block  7  and 
blade  6.  Plate  7,  say,  once  a  month  with  00  emery  cloth. 

Should  anything  happen  to  seriously  injure  the  parts  on 
top  of  relay  4,  Plate  5,  as,  for  instance,  something  falling 
on  them  and  smashing  the  whole  thing  so  badly  that  it  could 
not  readily  be  put  back  into  shape,  then  new  parts  can  be 
obtained  from  the  factory.  In  order  to  remove  the  old  parts, 
take  out  three  screws  in  the  top  of  block  10,  Plate  7,  the 
same  being  countersunk  into  the  block — two  on  one  side 
of  the  brass  parts  and  one  on  the  other;  disconnect  the  wires 
from  the  parts;  take  out  plunger  5,  as  per  former  directions, 
and  you  can  then  lift  the  block  off  and  replace  it  with  a 
new  one.  The  block  should  be  ordered  complete  with  the 
parts  assembled.  Should  it  ever  become  necessary  to  remove 
the  coil  of  relay  4,  Plate  5,  first  proceed  as  before  directed, 
and  remove  block  10,  Plate  7.  Having  removed  this  block 
you  will  see  three  screws  in  the  top  of  the  coil  casing.  Take 
out  these  screws  and  disconnect  the  two  wires  which  lead 
from  the  coil,  and  disconnect  wires  (two  of  them)  X,  Plate  5. 
You  may  then  lift  the  coil  out,  and  replace  it  with  a  new 
one  if  necessary. 

The  instruction  given  for  removing  the  top  and  the  coil 
of  relay  4,  Plate  5,  applies  equally  to  all  the  other  relays; 
just  remove  the  screws  in  the  top  of  the  block  (the  screws 
are  countersunk  in  all  cases),  disconnect  the  wires,  remove 
the  relay  plunger,  and  the  whole  thing  comes  off. 

Starting  anode  relay  resistance  1,  Plate  5,  is  in  series  with 
starting  anode  relay  8,  Plate  5  (also  see  Plate  2),  the  purpose 
of  this  resistance  being  to  limit  the  amount  of  current  flow- 
ing through  the  coil  of  the  relay.  It  is  connected  permanently 
into  the  circuit  of  the  relay  magnet  coil. 

Resistance  coil  9,  Plate  5,  is  connected  in  series  with  the 
contacts  of  series  underload  relay  11,  Plates  5  and  7.  (You 
cannot  see  this  relay  in  Plate  5.  It  is  under  arrow  head  11). 
This  resistance  is  not  in  series  with  the  relay  coil,  but 
serves  to  limit  the  flow  of  current  through  the  starting  anode, 
Plate  2.  But  for  this-  resistance  the  flow  of  current  through 
the  starting  anode  would  be  so  heavy  thai  there  would  be 
liability  of  damage  to  the  tube. 

Resistance  coils  1  and  9,  Plate  5,  may  be  removed  simply 
by  pulling  them  out  of  their  clips  as  you  would  a  cartridge 
fuse.  Resistance  coil  3  may  be  removed  by  disconnecting 
the  wires  attached  to  it,  and  taking  out  the  screw  which 
holds  the  carrying  clip  to  the  panel. 

Shaking    Magnet. — The    action    of    the    rectifier    is    made 


446  MOTION    PICTURE    HANDBOOK 

automatic  by  means  of  shaking  magnet  13  and  relay  8,  Plate  5 
and  7.  These  magnets,  therefore,  of  course,  fill  a  very  respon- 
sible position.  Part  15,  Plates  5  and  7,  is  so  made  that  it 
brings  the  tube  back  to  the  vertical  position  after  it  has 
been  rocked  by  the  action  of  the  shaking  magnet,  through 
force  of  gravity.  Should  the  tube  at  any  time  fail  to  rock 
to  the  vertical  position,  it  13  most  likely  due  to  friction  in 
spindle  16,  Plates  5  and  7.  This  friction  may  be  overcome 
by  means  of  a  drop  or  two  of  oil  on  the  bearing  surfaces, 
just  behind  the  nut  on  the  end  of  the  bolt  and  at  the  back 
of  the  spindle.  It  is  also  possible  that  dirt  may  work  in 
beside  plunger  17,  Plates  5  and  7.  This  plunger  may  be 
removed  by  taking  out  the  bolt  in  the  fork  at  its  lower  end, 
and  driving  out  the  small  pin  in  nut  17  at  the  top  of  the 
plunger.  The  plunger  can  then  be  dropped  down  enough  to 
clean  it. 

Should  plunger  20  of  relay  8,  Plates  5  and  7,  fail  to  work, 
it  may  be  taken  out  and  examined  by  removing  the  split 
key  at  its  upper  end  and  pulling  the  plunger  out  at  the 
bottom. 

Should  the  rectifier  at  any  time  fail  to  act,  the  first  thing 
to  look  at  and  test  will  be  your  fuses,  including  those  on 
the  front  of  the  panel.  Don't  try  anything  else  until  you 
have  tested  the  fuses.  It  is  quite  possible  you  may  get  a  spark 
at  the  carbons  of  the  lamp  when  one  of  the  fuses  is  burned  out. 

WESTINGHOUSE  MERCURY  ARC  RECTIFIER 

In  Plate  1  we  get  .a  view  of  the  front  of  the  Westinghouse 
Mercury  Arc  Rectifier  designed  for  use  on  projection  cir- 
cuits. This  machine  is  built  in  30,  40  and  50  ampere  sizes, 
the  general  design,  characteristics  and  appearance  being  the 
same  for  all. 

Each  outfit  consists  of  a  cast  iron  main  frame  on  which 
is  mounted  (a)  an  auto-transformer,  L-L,  Plate  3;  (b)  re- 
actance coil,  Q,  Plate  3;  (c)  a  tilting  mechanism,  B,  D,  K, 
P,  Plate  2;  (d)  a  relay,  I,  Plate  3;  (e)  a  five-point  dial  switch, 
Plate  1,  and  E,  F,.  G,  H,  I,  Plate  2;  (f)  'adapting  links,  Plate 
1;  (g)  a  tube  and'tube  holder,  24,  25,  26,  Plate  4,  all  inclosed 
in  a  perforated  sheet  steel  cover.  The  machine  presents  a 
neat,  compact  appearance  and  occupies  but  little  floor  space. 

In  Plate  2,  we  have  a  view  of  the  rectifier  with  the  per- 
forated sheet  steel  cover,  the  cover  of  the  dial  switch  and  the  tube 
removed.  At  the  bottom,  in  the  corner,  is  the  tilting  magnet, 
P,  the  operation  of  which  is  very  clearly  shown.  When 
magnet  P  is  energized,  its  plunger,  K,  moves  downward 


FOR  MANAGERS  AND  OPERATORS 


447 


INSTRUCTION) 
CARD          / 


FRONT 

PERFORATED 

COVER 

INSTRUCTION 

CARD 

FRAME 


Plate  1,  Figure  221. 


448  MOTION    PICTURE    HANDBOOK 

and  tilts  or  rocks  the  tube.  The  construction  of  the  dial 
switch  is  also  very  clearly  shown,  the  round  buttons,  E, 
being  dummies,  over  which  switch  contact  fingers  G  slide 
from  one  wide  contact,  F,  to  another.  At  the  bottom  are  four 
wires,  L,  M,  N,  O,  coiled  up  and  terminating  in  brass  spring 
clips.  These  are  the  leads  which  connect  to  the  anodes  and 
cathodes  of  the  tube,  as  per  9-9-12-29,  Plate  4. 

In  Plate  3  we  have  a  rear  view  of  the  outfit,  showing,  near 
the  bottom,  the  reactance  Q,  and  above  it  the  auto-trans- 
former L-L.  In  Plate  3  we  see  at  the  left  the  D.  C.  leads, 
A,  B,  which  connect  to  the  arc  lamp  circuit,  the  inside  one,  A,  be- 
ing the  negative  and  the  outside  or  left  hand  one  B,  the  positive. 
The  positive  must,  of  course,  connect  through  the  machine 
table  switch  to  the  top  carbon  arm  of  the  lamp,  and  the 
negative  through  the  machine  table  switch  to  the  bottom 
carbon  arm  of  the  lamp,  The  A.  C.  leads,  H,  are  seen  in 
Plate  3  at  right  hand  side.  These  leads  connect  directly, 
through  a  switch  and  fuse,  to  the  alternating  current  supply. 
In  the  center,  at  the  top  of  Plate  3,  is  relay  magnet  1,  the  pur- 
pose of  which  will  be  explained  further  on. 

The  Auto-Transformer,  L-L,  Plate  3,  consists  of 'an  iron 
core  with  a  winding  of  heavy  copper  wire.  It  is  similar  to 
an  ordinary  transformer,  except  that  its  connections  are 
such  that  in  effect  it  has  only  one  winding,  whereas  the 
ordinary  transformer  has  two,  viz:  a  primary  and  secondary. 
Its  function  is  to  change  the  voltage  of  the  A.  C.  supply 
circuit  to  the  pressure  required  at  the  arc.  The  center  point 
of  the  winding  also  forms  the  negative  terminal  of  the  arc 
circuit,  as  per  3,  4,  4,  in  diagram,  Plate  5.  (See  Fig.  169, 
Page  358.) 

Reactance  Coil. — The  reactance  coil,  Q,  Plate  3,  is  similar 
in  appearance  and  construction  to  a  transformer.  It  is  con- 
nected into  the  alternating  current  circuit  for  the  purpose 
of  limiting  current  flow  when  the  carbons  are  brought  to- 
gether to  strike  the  arc,  to  a  value  that  will  not  be  injurious 
to  the  tube;  also  it  operates  to  insure  steadiness  of  the  arc 
and  to  prevent  any  wide  fluctuations  of  the  current  when 
the  length  of  the  arc  is  changed.  The  general  effect  is  to 
make  the  arc  much  easier  to  handle. 

Tilting  Mechanism. — Each  rectifier  is  provided  with  an 
automatic  tilting  device,  consisting  of  parts  B,  D,  K  and  P, 
Plate  2.  This  device  is  so  connected  that  the  closing  of 
the  carbons  energizes  magnet  P  and  thus  causes  the  tube  to 
tilt,  which  makes  the  rectifier  a  self-starter.  The  mechan- 
ism is  operated  by  magnet  P,  Plate  2,  the  pull  of  which  is 


FOR  MANAGERS  AND  OPERATORS 


449 


Plate  2,  Figure  222. 


A,  mounting  screws  for  relay;  B,  upper  bulb  spring  holder;  C,  lower 
bulb  spring  holder;  D,  brass  guide  for  tilting  rod;  E,  dummy  contacts; 
F,  contacts;  G,  contact  finger;  H,  contact  arm;  I,  insulating  support  for 
contact;  J,  bulb  holder  casting;  K,  tilting  magnet  plunger;  L,  M,  N,  O, 
wires  having  spring  contacts  at  end  to  connect  to  tube  anodes  and 
cathodes. 


450  MOTION    PICTURE   HANDBOOK 

applied  to  the  tube  by  coil  spring  B,  Plate  2,  as  shown.  A 
spring  is  used  instead  of  a  rod  in  order  to  prevent  the  tube 
from  being  subjected  to  unnecessary  and  violent  shock. 

The  Relay,  1,  Plate  3,  is  another  magnet,  used  to  operate 
the  contacts  which  open  the  tilting  magnet  circuit  when  the 
arc  is  started,  thus  preventing  the  tube  from  tilting  at  any 
other  time.  But  for  this  cutout  the  tilting  magnet  would 
continue  to  operate,  and  the  tube  would  be  tilted,  or  rocked 
continuously. 

The  Five  Point  Dial  Switch,  Plates  1  and  2,  is  used  to 
change  the  connections  to  the  reactance  coil  in  such  way  as 
to  vary  the  arc  current  to  any  desired  value  within  the 
limits  of  the  machine.  This  switch,  as  its  name  indicates, 
gives  five  different  values  of  current,  and  the  change  may 
be  made  from  one  point  to  another  without  breaking  the  arc. 

The  Upper  Adapting  Link,  17,  Plate  4,  is  |  for  the  purpose 
of  changing  the  connections  to  the  reactance  coil,  so  as  to 
provide  proper  voltage  adjustment  at  the  arc  for  different 
supply  circuit  voltages.  In  other  words,  the  A.  C.  supply 
may  be  220  or  110  on  the  face  of  it,  whereas  the  actual 
pressure  in  the  theatre,  owing  to  drop  in  line,  etc.,  may  be 
anywhere  between  210  and  230,  or  105  and  115  volts.  By 
means  of  this  link  it  is  possible  to  provide  for  these  varia- 
tions and  make  a  connection  suited  to  the  actual  voltage, 
which  easily  may  be  determined  by  using  an  A.  C.  voltmeter. 
If  a  voltmeter  is  not  available  the  lighting  company  should 
be  requested  to  make  the  test. 

The  Lower  Link  Connector,  18,  Plate  4,  is  used  in  emer- 
gency, to  transfer  the  arc  from  the  tube  circuit  to  direct 
operation  on  the  alternating  current  circuit,  in  case  the  tube 
should  fail  or  something  else  happen  to  the  rectifying  side 
of  the  machine.  For  direct  current  operation  (rectification) 
this  link  should  be  placed  so  as  to  join  the  lower  of  the  three 
terminals  and  the  upper  right  hand  terminals,  marked  "D.  C. 
Arc";  for  alternating  current  operation  the  link  should  join 
the  lower  terminal  and  the  upper  left  hand  terminal  marked 
"A.  C.  Arc."  Be  sure  that  the  wing  nuts  are  well  tightened 
so  as  to  clamp  the  links  firmly. 

The  Tube  is  a  glass  vessel  into  which  a  small  amount 
of  mercury  has  been  placed,  and  from  which  all  the  air  has  been 
removed,  causing  a  vacuum.  The  general  characteristics  of 
its  operation  have  been  described  under  "General  Remarks," 
Page  428.  It  has  four  terminals,  the  upper  ones  being  the 
graphite  anodes,  the  smaller,  lower  one  the  starting  anode 


FOR    MANAGERS    AND    OPERATORS  451 


Plate  3,  Figure  223. 


A,  positive  D.  C.  lead;  B,  negative  D.  C.  lead;  C,  relay  contact  disc; 
D,  transformer  lead  tags;  E,  rear  end  of  bulb  holder  shaft  In  ball  bear- 
ing; F,  reactance  lead  tags;  G,  fibre  clamping  blocks  for  reactance  coil: 
H,  A.  C.  leads;  I,  relay  magnet;  J,  relay  contact  stud;  K.  transformer 
iron;  L,  transformer  coil;  M,  clamping  block  for  transformer  iron; 
N,  mounting  bolt  for  transformer;  P,  cotter  pin;  Q,  reactance  coil; 
R,  reactance  iron;  S,  reactance  coll  leads. 


452  MOTION    PICTURE    HANDBOOK 

and  the  large  lower  one  the  cathode;  both  the  two  lower  are 
of  mercury.  These  various  terminals  are  connected  to  coiled 
leads  L,  M,  N,  O,  Plate  2,  by  means  of  brass  spring  clips, 
as  at  9,  9,  12,  29,  Plate  4. 

Installation. — The   rectifier   will   be   received  in  two   ship- 
ments.    The  glass  tube,  carefully  packed  in  a  special  crate, 
is   usually   sent   by  express,   whereas   the   remainder   of   the 
outfit,  being  the  completely  assembled  rectifier   (except  the 
tube)  all  ready  for  operation,  will  probably  be  sent  by  freight. 
When   the   outfit   is  received,   remove  it  from  its   case   and 
place  in  the  location  selected.    Remove  the  perforated  sheet 
steel    cover    and    connect   the    A.    C.    feed  wires    to    rectifier 
leads   H,    Plate   3,   through   a   line  switch   and   fuses,  as    per 
instructions  mounted  on  front  cover  of  the  rectifier.     Con- 
nect   leads    D    —    and    C    +    to    the    machine    table    switch 
with  the  positive  (+),  B,  Plate  3,  connected  to  the  top  car- 
bon arm  and  the  negative  ( — ),  A,  Plate  3,  connected  to  the 
lower  carbon  arm.     Open  the  crate  containing  the  tube  by 
removing   two   screws   from   the   center   of   each   side.      Lift 
the   outer   portion   of  the  crate  away,  which  will   leave   the 
tube  suspended  from  the  inner  portion  of  the  crate.     Loosen 
the   linen   tape   and  lift  the  tube    carefully   from   the   holder. 
Turn    the    tube    upside  (down,    slowly    and    very    carefully, 
making    sure    that    the    mercury    runs    slowly    into    the    two 
bottom  terminals.     The  mercury  in  a  tube  that  is  in  good 
condition  should  make  a  sharp  metallic  click  when  passing 
from    one    end   of   the   tube   to    the   other.      Grasp    the   tube 
firmly  in  both  hands,  the  right  at  the  extreme  top,  and  the 
left  grasping  the  mercury  terminals,  and,  guarding  carefully 
against  collision,  slide  the  tube  into  the  lower   spring  clips 
of  the  tube  holder,  taking  care  that  the  springs  do  not  cause 
the  tube  to  slide  into  the  tube  holder  with  a  jar. 

Be  very  careful  not  to  allow  the  smaller  mercury  terminal 
to  strike  the  tube  holder,  or  any  other  object,  as  it  is  quite 
easily  broken.  After  the  lower  part  of  the  tube  is  properly 
placed,  push  the  top  part  gently  back  into  the  upper  spring. 
If  it  becomes  necessary  to  remove  the  tube,  as  in  case  of 
changing  location  of  outfit,  the  same  method  of  handling 
should  be  followed.  Connect  the  tube  leads  (that  is,  the 
flexible  wires  attached  to  the  terminal  board  below  the 
tube  marked  L,  M,  N,  and  O,  Rlate  2)  to  the  tube,  as  shown 
at  9,  9,  12,  29,  Plate  4.  The  wires  may  easily  be  traced  in 
Plate  4.  Connect  wire  4,  Plate  2f  to  the  upper  left  hand  tube 
terminal,  9,  Plate  4 ;  the  lead  M  to  the  small  lower  tube  terminal, 
29,  Plate  4;  lead  N  to  the  large  lower  terminal,  12,  Plate  4,  and 


FOR    MANAGERS    AND    OPERATORS 


453 


14 


Plate  4,  Figure  224. 


1,  lifting  lug;  2,  name  plate;  3,  mounting  bolt  for  slate  panel;  4,  cast 
iron  cover  for  dial  switch;  5,  dial  switch  handle;  6,  rear  perforated 
cover;  7,  cable  containing  leads;  8,  transformer;  9,  spring  clip  on  side 
terminal  of  bulb;  10,  mercury  pool  in  bulb;  11,  lead  to  side  terminal 
of  bulb;  12,  spring  clip  on  large  lower  terminal  of  bulb;  13,  resistance 
box  terminal;  14,  main  cast  iron  frame;  15,  resistance  box;  16,  stud 
for  link  connector;  17,  upper  link  connector;  18,  lower  link  connector; 
19,  end  of  relay  contact  stud;  20,  transformer  leads;  21,  stud  for  front 
perforated  cover;  22,  bolt  for  front  perforated  cover;  23,  mounting 
bolt  for  transformer;  24,  upper  bulb  holder  spring;  25,  bulb;  26,  lower 
bulb  holder  spring;  27,  mounting  strap  for  tilting  magnet  and  resistance 
box;  28,  lug  for  tilting  magnet  and  resistance  box;  29,  spring  clip  on 
small  lower  terminal  of  bulb;  30,  tilting  magnet  frame;  31,  tilting 
magnet  coil;  32,  terminal  board;  33,  connector  on  terminal  board;  84, 
wiring  from  terminal  board;  35,  dial  switch  pointer. 


454  MOTION    PICTURE   HANDBOOK 

lead  0,  the  last  one,  to  the  right  hand  upper  terminal,  9,  Plate  4. 
The  upper  link  connector  on  the  slate  panel  at  the  top  of  the  out- 
fit should  now  be  connected  to  suit  the  voltage  of  the  supply 
wires,  which  should  be  determined  by  actual  test  with  a 
reliable  voltmeter.  It  may  be  noted  in  this  connection  that 
the  voltage  for  which  the  link  is  set  should  be  tested  when 
the  rectifier  is  in  actual  operation,  since  the  voltage  of  the 
line  may  decrease  with  the  added  load.  It  is  unlikely  that 
once  this  connection  is  properly  made  it  ever  will  be  neces- 
sary to  change  it.  The  outfit,  without  any  further  adjust- 
ment, is  now  ready  for  operation. 

Plate  5  shows  the  wiring  diagram  for  the  three  types  of 
the  Westinghouse  rectifier.  These  diagrams  are,  I  believe, 
of  questionable  value  to  the  average  operator.  However, 
there  are  a  goodly  number  who  will  be  able  to  make  use  of 
them.  The  upper  one  is  for  the  30  ampere,  110-220  volt, 
the  center  one  for  the  40  ampere,  110-220  volt,  and  the  lower 
one  for  the  50  ampere,  110  volt  rectifier. 

Operation. — With  fuses  of  proper  capacity  in  place,  close 
both  the  A.  C.  line  switch  and  the  machine  table  switch  and 
bring  the  carbons  together,  whereupon  the  tube  will  rock, 
a  spark  appearing  between  the  two  mercury  pools  at  each 
tilt  until  the  arc  starts,  when  the  whole  tube  will  light  up 
and  come  to  rest  in  a  vertical  position.  The  carbons  should 
be  instantly  separated  until  the  greatest  amount  of  light  is 
obtained  on  the  screen. 

Where  the  size  of  the  theatre  and  equipment  only  justifies 
the  purchase  of  a  single  rectifier,  the  problem  of  blending 

one  reel  into  the  next 
has  been  solved  as  de- 
scribed below:  The 
only  extra  equipment 
necessary  is  a  compen- 
sator or  economy  coil 
such  as  is  usually 
found  in  a  theatre  using 
alternating  current,  and 
Plate  6,  Figure  226.  a  four-pole,  double 

throw   switch. 

The  wiring  is  shown  in  Plate  6  and  requires  no  elaborate 
explanation.  By  means  of  this  plan  the  change-over  may  be 
made  without  any  very  seriously  objectionable  indication 
of  the  fact  on  the  screen.  The  operator,  we  will  say,  is 
showing  the  first  reel  of  a  feature  film  on  machine  No.  1, 
which  is  fed  from  the  rectifier,  the  switch  being  thrown  to 


FOR    MANAGERS    AND    OPERATORS  455 


2\  Auto  -Transformer  [4 

^o  ft  o  Q  0  Q  Q  o  o_o  sT  Q  Q_Q  QAoJ>JL0Aft.1J 


Plate  5,  Figure  225. 


456 


MOTION    PICTURE   HANDBOOK 


the  left.  About  one  minute  before  the  end  of  the  reel  is 
reached  he  throws  the  switch  to  the  right,  starting  the  arc 
on  machine  No.  2  through  the  rectifier,  while  machine  No.  1 
is  transferred  to  the  alternating  current  supply  of  the  com- 
pensator, and  the  reel  is  completed  in  this  manner.  This 
gives  the  carbons  on  No.  2.  time  to  burn  to  their  proper 
brilliancy  on  D.  C,  ready  to  begin  the  second  reel.  The 
process  is  repeated  toward  the  end  of  the  second  reel  on 
machine  No.  2.  The  procedure  may,  if  desired,  be  reversed; 
that  is  to  say,  starting  machine  No.  2  on  alternating  current 
and  later  changing  it  to  direct  current.  However,  the  first 
mentioned  will  be  found  more  satisfactory,  as  it  takes  a  short 
while  for  the  direct  current  to  burn  the  crater  properly. 


Always  do  it  just  as  though 
the      boss      was      around. 


FOR    MANAGERS    AND    OPERATORS  457 


The  Mechanism 

General  Instructions  Applying  to  All  Machines 

MACHINES  are  very  frequently  sold  to  small  town  ex- 
hibitors who  in  the  very  nature  of  things  are  unable 
to  employ  competent  operators,  and  who  themselves 
have  little  or  no  knowledge  of  mechanics.  When  a  part 
wears  or  breaks  they  are  at  a  loss  as  to  the  method  of  pro- 
cedure necessary  to  remove  the  same  and  replace  it  with  a 
new  one;  also  they  are  unable  to  make  the  necessary  ad- 
justments properly.  These  men  are  doing  a  distinctly  meri- 
torious work  in  supplying  theatrical  amusement  to  what  in  the 
aggregate  amounts  to  millions  of  people,  who  would  otherwise 
be  deprived  of  the  pleasures  of  moving  pictures.  They  are  en- 
titled to  detailed  information  concerning  these  matters,  and  ANY 

ADDITION  TO  THEIR  KNOWLEDGE  WHICH  ENABLES  THEM  TO  PUT  ON  A 
BETTER  PICTURE  IS  ADDING  TO  THE  PLEASURE  OF  ALL  THESE  MILLIONS 
OF  PEOPLE  WHO  PATRONIZE  SMALL  TOWN  OR  VILLAGE  MOVING  PICTURE 
PLAYHOUSES. 

Not  only  is  this  true,  but,  as  a  matter  of  fact,  even  com- 
petent experienced  operators  are  sometimes  at  their  wits 
end,  and  commit  very  serious  blunders,  simply  because  but 
few  operators,  except  those  in  very  large  cities,  are  able  to  get 
experience  on  all  the  different  moving  picture  mechanisms. 

Some  operators  object  to  supplying  detailed  instructions 
on  projector  mechanisms.  I  think,  however,  to  omit  these 
instructions  would  be  not  only  unfair  to  the  industry  as  a 
whole,  but  also  to  the  audiences  who  patronize  moving  pic- 
ture theatres,  and,  moreover,  to  the  operator  himself.  The 
claim  that  such  instructions  will  have  a  tendency  to  create 
operators  has,  in  my  opinion,  but  little  weight,  and  even  if 
it  did,  the  operator,  important  as  is  his  function,  is  but  one 
cog  in  the  mechanism  of  the  moving  picture  industry,  and 
we  must  perforce  look  to  the  well-being  of  the  industry  as 
a  whole. 

There  are  certain  general  instructions  which  apply  to  all 
projection  machines,  as  follows: 

General  Instruction  No.  1. — Oil — There  is  a  tremendous 
amount  of  absolutely  unnecessary  damage  done  both  t  > 


458  MOTION    PICTURE   HANDBOOK 

projection    machines    and    film,    through    lack    of    knowledge 
and  care  in  the  lubrication  of  projectors. 

The  much  advertised  patent  oils  are,  I  believe,  without  ex- 
ception, absolutely  unfitted  for  projection  machine  lubrication, 
and  their  use  will,  I  am  firmly  convinced,  shorten  the  life  of  a 
projector  by  fully  one-third,  if  not  more. 

Too  thin  an  oil  is  likely  not  only  to  have  inferior  lubricat- 
ing properties,  but  also  a  decided  tendency  to  run  out  the 
bearing^  and  be  thrown  off  by  centrifugal  force,  all  too 
often  landing  on  the  film  or  lens.  Too  thick  an  oil,  on  the 
other  hand,  is  likely  to  be  gummy,  to  collect  dirt,  and  to 
remain  in  the  bearings  too  long.  One  rule  should,  however, 
be  rigidly  adhered  to  by  all  operators. 

NEVER,  UNDER  ANY  CIRCUMSTANCES,  USE 
MORE  THAN  ONE  DROP  OF  OIL  IN  ANY  MOVING 
PICTURE  MACHINE  BEARING. 

Anything  more  is  worse  than  useless,  since  one  drop  is 
ample  for  all  purposes  of  lubrication:,  and  the  excess  will 
simply  run,  or  be  thrown  off,  and  make  a  dirty  mess. 

In  my  previous  books  I  recommended  a  good  grade  of  light 
dynamo  oil  for  the  projector  bearings.  I  see  no  reason  to  change 
this  recommendation.  This  oil  can  be  procured,  in  bulk,  from 
any  oil  dealer,  and  should  cost  not  more  than  25  cents  a 
quart.  The  Projection  Department  of  the  Moving  Picture 
World  expended  a  good  deal  of  energy  and  time  in  trying 
to  locate  a  really  good  projector  lubricant  which  could  be 
bought  at  a  reasonable  price  from  film  exchanges.  The 
Latchaw  oil  was  found,  after  exhaustive  test,  to  be  the  only 
one  to  fill  the  bill,  and  it  received  the  indorsement  of  the 
department.  That  however,  was  nearly  two  years  ago,  and 
while  the  oil  was  most  excellent  at  that  time  I  do  not  know  what 
it  is  now,  or  even  whether  or  not  it  is  still  on  the  market. 

For  the  gears  of  the  projector  there  are  several  very  good 
lubricants,  among  them  automobile  cylinder  oil,  bicycle 
chain  lubricant,  automobile  axle  grease,  and  a  good  grade  of 
vaseline.  Beeswax  also  has  been  successfully  used  by  some. 
A  light  lubricating  oil  is  not  suitable  for  gears.  However,  no 
matter  what  is  used,  if  the  machine  is  of  the  open  type — that 
is  to  say,  has  no  casing  and  the  gears  run  in  the  open,  there 
will  be  dust  and  dirt  constantly  collecting  which,  uniting  with 
the  oil,  forms  a  grinding  paste.  It  is,  therefore,  advisable  to 
wasli  the  gears  of  such  machines  thoroughly  once  or  twice 
a  week.  This  may  easily  be  done,  without  removing  the 
mechanism  from  the  table,  by  placing  a  shallow  dish  or  pan 
under  the  gears  while  you  turn  the  crank  slowly,  at  the 


FOR    MANAGERS    AND    OPERATORS  459 

same-  time  flooding  the  gears  with  kerosene  from  an  or- 
dinary squirt  can  such  as  is  used  to  oil  the  machine.  If 
preferred  the  mechanism  may  be  taken  off  the  table,  im- 
mersed in  gasoline  and,  first  having  removed  the  lenses  and 
the  crank,  given  a  few  turns  while  the  mechanism  is  in  the 
bath.  This  washes  out  both  the  gears  and  bearings  very 
thoroughly.  If  the  intermittent  runs  in  an  oil  well,  plug 
up  the  oil  well  oil  hole  before  immersing  the  machine. 

If  the  intermittent  movement  of  your  machine  runs  in  an 
oil  well  a  good  grade  of  lubricant  should  be  used  therein. 
Some  manufacturers  recommend  high  grade  vaseline  for 
this  purpose,  which  should  be  melted  and  poured  in. 

Personally  the  writter  does  not  regard  vaseline  as  a  satis- 
factory lubricant.  He  believes  that  a  good  medium-bodied 
oil,  such  as  a  fairly  heavy  dynamo  oil,  is  much  better.  But 
whatever  you  use  in  the  oil  well,  remember  that  the  intermittent 
is  subjected  to  exceedingly  heavy  service,  therefore,  unless  the 
lubricant  be  high  grade  you  may  expect  the  cam  pins  to  wear 
very  rapidly. 

General  Instruction  No.  2. — Where  the  old  style  friction 
take-up  is  used  it  is  of  the  utmost  importance  that  the  take- 
up  tension  be  set  just  barely  tight  enough  to  take  up  the 
entire  reel  of  film.  Anything  in  addition  to  this  is  not  only 
bad,  but  very  bad.  A  minute's  consideration  will  convince  you 
of  the  importance  of  this  matter.  Throughout  the  entire 
process  of  rewinding  the  friction  of  the  take-up  will  exert 
exactly  the  same  amount  of  pull  on  the  spindle  which  carries 
the  take-up  reel.  When  the  film  first  begins  to  wind  on  the  hub 
of  the  lower  reel  the  take-up  is  pulling  on  the  take-up  spindle 
exactly  as  hard  as  it  is  when  the  process  of  rewinding  is 
near  its  completion,  but  in  the  beginning  the  film  is  winding 
on  the  \*/i  inch  hub,  whereas  at  the  end  it  is  winding  on  the 
outside  diameter  of  a  film  roll  ten  or  more  inches  in  diame- 
ter. Therefore,  since  the  take-up  pull  is  constant  on  the 
spindle,  the  actual  pull  exerted  on  the  film  at  the  beginning  is 
very  many  times  greater  than  it  is  at  the  end.  This  means  that 
the  film  is  wound  too  tightly  in  the  beginning  and  too  loose- 
ly at  the  end,  and  that  any  unnecessary  take-up  tension  only 
serves  to  aggravate  the  abnormally  heavy  pull  at  the  begin- 
ning of  the  process  of  rewinding;  moreover,  it  adds  to  the 
tendency  to  lose  the  lower  loop  in  the  earlier  part  of  the 
run,  besides  the  constant  danger  of  pulling  weak  patches  in 
two.  Excessive  tension  is,  in  every  way,  deterimental,  there- 
fore be  very  careful  and  don't  set  your  take-up  tension  any 
tighter  than  is  necessary  to  complete  the  process  of  rewinding. 


460  MOTION    PICTURE    HANDBOOK 

There  have  of  late  been  some  improved  tension  equalizers 
invented  which  equalize  the  take-up  pull  throughout  the 
entire  run.  They  should  by  all  means  promptly  be  adopted 
by  machine  manufacturers. 

General  Instruction  No.  3. — It  is  of  the  utmost  importance 
that  the  sprockets  of  your  machine  be  kept  perfectly  clean. 
This  is  particularly  true  of  the  intermittent  sprocket.  The 
best  method  of  cleaning  them  is  as  follows:  Procure  an 
ordinary  cheap  toothbrush  and  a  wide-mouthed  bottle  or 
a  small  tin  can  with  a  cover.  If  a  bottle  is  used  punch  a 
hole  in  the  cork  and  fasten  the  tooth  brush  therein  in  such 
position  that  it  will  reach  the  bottom  of  the  bottle  when  the 
cork  is  in.  If  a  can  be  used  do  the  same  thing  with  the  lid. 
Now  fill  your  bottle  or  can  with  kerosene,  and  just  as  soon 
as  the  least  bit  of  gum  or  dirt  begins  to  gather  on  the  face 
of  the  intermittent  sprocket  scrub  it  off  with  the  tooth- 
brush wet  with  kerosene.  Go  over  your  sprockets  carefully 
once  every  day  and  be  sure  they  are  perfectly  clean.  Dirt 
on  the  upper  or  lower  sprocket  will  have  a  decided  tendency 
to  cause  the  losing  of  the  loops. 

Dirt  on  the  intermittent  sprocket  will  make  the  picture  jump 
on  the  screen,  not  sometimes  but  always. 

It  is  an  astonishing  fact  that  many  operators  do  not  seem 
to  grasp  this  simple  and  seemingly  self-evident  idea.  I  have 
actually  known  of  a  projection  mechanism  being  shipped  to  the 
factory  from  a  distance  of  two  thousand  miles,  with  a  complaint 
that  the  "picture  jumped  terribly."  On  examination  the  face  of 
the  intermittent  sprocket  was  found  to  be  covered  with  gum 
and  dirt.  This  was  washed  off,  the  machine  tried  out  and 
the  picture  found  to  be  as  steady  as  a  rock.  Imagine,  if  you 
can,  sending  a  machine  more  than  two  thousand  miles  merely 
to  have  the  face  of  .the  intermittent  sprocket  cleaned  off;  a 
thing  the  operator  could  have  done  in  less  than  two  minutes, 
by  the  aid  of  a  little  kerosene  and  a  ten-cent  toothbrush. 

General  Instruction  No.  4. — It  is  important  that  the  sprock- 
ets of  your  machines  be  kept  in  perfect  line  with  each 
other  and  with  the  aperture.  I  cannot  give  definite  instruc- 
tions as  to  how  to  test  the  lining  of  the  sprockets,  since 
this  will  vary  with  each  different  make  of  machine.  The 
meaning  is  set  forth  in  Fig.  227,  in  which  the  dotted  line 
is  presumed  to  be  exactly  central  sidewise  in  the  aperture 
and  perpendicular  thereto.  The  upper,  lower  and  intermit- 
tent sprockets  must  be  exactly  central  sidewise  with  this 
line,  or,  in  other  words,  the  teeth  on  each  side  of  each 
sprocket  must  be  equidistant  from  the  line.  This  may  be 


FOR  MANAGERS  AND  OPERATORS 


461 


roughly  tested,  so  far  as  the  intermittent  and  upper  sprocket 
be  concerned,  as  follows:  Using  a  piece  of  new  film,  of  some 
make  that  is  known  to  have 
perfect  perforations,  thread  a 
short  piece,  say  one  foot  long, 
into  the  machine,  engaging  it 
with  the  teeth  of  the  upper 
and  intermittent  sprockets, 
and  closing  the  idlers.  Turn 
the  fly-wheel  backward  until  the 
film  is  stretched  tightly,  being 
careful  that  the  sprocket  teeth 
are  in  the  center,  sidewise,  of 
the  sprocket  holes.  If  the  upper 
and  lower  sprocket  and  the 
aperture  are  not  in  line  the  fact 
will  be  detected  by  the  film- 
edge  not  being  in  line  with  the 
tracks  on  the  aperture  plate,  or 
the  aperture  plate  not  being 
central  in  the  film.  If  the  film 
seems  to  bear  equally  on  both 
edges  of  both  sprockets  and  the 
aperture  plate  tracks  are  not 


Figure  227. 


straight  with  the  film,  it  would  indicate  the  probability  that 
the  aperture  plate  itself  is  out  of  true.  In  some  machines 
this  may  be  easily  remedied;  in  others  the  aperture  plate 
cannot  possibly  be  out  of  true  and  the  indication  would  be 
that  both  the  upper  and  intermittent  sprocket  is  too  far  over 
to  the  right  or  left.  Before  making  this  test,  however,  it  is 
essential  that  you  be  sure  your  intermittent  sprocket  shaft 
is  in  exact  alignment  with  the  cam  shaft. 

General  Instruction  No.  5. — The  intermittent  movement, 
that  is  to  say,  the  star  and  cam,  or  in  the  case  of  the  Power 
Six  the  cam  and  cross,  must  be  set  up  closely  enough  that 
there  is  very  little  circumferential  play  in  the  intermittent 
sprocket.  This  must  not,  however,  be  carried  to  excess. 
It  is  not  wise  to  attempt  to  eliminate  all  circumferential  play 
in  the  intermittent  sprocket  when  the  machine  is  cold.  If 
you  do,  when  the  machine  becomes  warm  the  expansion  of  the 
parts  through  heat  will  set  up  undue  friction,  and  cause  excessive 
and  unnecessary  wear.  It  is  a  mistake  to  suppose  that  a  little 
circumferential  play  in  the  intermittent  sprocket  will  cause 
unsteadiness  in  the  picture.  It  does  no  harm  whatever, 
though  it  does  not  follow  that  an  excess  of  movement  would 


462  MOTION   PICTURE   HANDBOOK 

not  be  harmful.  Set  it  just  so  that  you  can  barely  detect 
some  movement  when  you  try  to  rock  the  sprocket  with 
your  finger.  Don't  try  to  adjust  the  intermittent  as  above  if  the 
cam  or  intermittent  shaft  bushings  are  worn.  Where  a  machine 
is  of  a  type  to  allow  of  its  being  done  I  would  strongly  advise 
managers  and  operators  to  have  a  complete  framing  carriage  on 
hand  all  ready  to  slip  into  the  machine. 

The  replacement  of  the  intermittent  sprocket,  star,  cam,  or 
their  shaft  is  a  very  delicate  operation,  and  one  which  really 
should  be  done  at  the  factory.  If  you  have  an  extra  framing 
carriage,  with  all  the  parts  assembled,  when  the  parts  be- 
come worn,  you  can  take  the  old  carriage  out,  put  in  the 
new  one,  and  send  the  old  one  to  the  factory,  by  parcel  post, 
where  it  will  be  repaired  in  the  best  possible  manner.  This 
latter  does  not  apply  to  Standard  or  Edison. 

General  Instruction  No.  6. — The  top  idler  on  the  gate  or 
whatever  takes  its  place  is  for  the  purpose  of  holding  the 
film  central  over  the  aperture,  guiding  the  film  down  into  the 
gate,  and  helping  to  eliminate  side  motion.  It  should  be 
kept  so  set  that  it  holds  the  film  snugly,  but  without  bind- 
ing, and  so  set  that  the  film  will  be  exactly  central  over  the 
aperture.  In  some  machines  the  position  of  this  guide 
is  fixed  and  cannot  be  altered;  in  others  it  may  be  altered, 
and  if  set  loosely  enough  to  allow  the  film  to  have  free  side 
play  there  is  likely  to  be  side  motion  of  the  picture  on  the 
screen.  Also  if  it  be  set  over  too  far  there  is  a  possibility 
of  the  sprocket  holes  showing  on  one  side  of  the  screen. 

General  Instruction  No.  7. — There  must  be  no  end  play 
whatever  in  the  intermittent  sprocket.  End  play  in  the  in- 
termittent sprocket  is  likely  to  produce  side  motion  in  the 
picture  on  the  screen.  It  does  not  necessarily  follow  that 
the  picture  will  have  a  side  motion  because  there  is  end  play 
in  the  intermittent  sprocket,  but  it  is  highly  probable  it 
will,  nevertheless. 

General  Instruction  No.  8. — It  is  a  serious  mistake  to  use 
an  intermittent  sprocket  after  the  teeth  have  become  ap- 
preciably worn.  The  wise  manager  or  operator  will  not 
attempt  to  save  money  by  using  an  intermittent  sprocket 
with  worn  teeth,  since  the  using  of  such  a  sprocket  is  bad 
from  any  and  every  point  of  view.  Worn  intermittent 
sprocket  teeth  are  very  hard  on  the  perforations  of  the  film 
and  very  apt  to  produce  unsteadiness  of  the  picture  on  the 
screen.  Worn  teeth  also  have  a  decided  tendency  to  cause 
the  teeth  to  climb  the  sprocket  holes,  thus  losing  the  lower 
loop.  The  intermittent  sprocket  teeth  do  all  the  work  of 


FOR    MANAGERS    AND    OPERATORS  463 

pulling  down  the  film  against  the  friction  of  the  tension 
shoes,  hence  are  subject  to  heavy  wear.  The  operator  should 
examine  his  intermittent  sprocket  teeth,  using  a  condensing 
lens  as  a  magnifying  glass,  every  few  days.  As  soon  as 
there  is  evidence  of  appreciable  wear  the  sprocket  should 
be  promptly  renewed.  The  same  thing  is  true  in  lesser 
degree  of  the  upper  and  lower  sprockets,  though  moderate 
wear  on  the  teeth  of  these  is  not  so  harmful;  moreover, 
these  sprockets  may  in  some  and  I  believe  in  all  makes  of 
projectors,  except  the  motiograph,  be  removed  and  turned 
end  for  end,  thus  presenting  an  entirely  new  tooth-surface 
to  the  film  when  one  side  of  the  teeth  has  become  worn. 
The  same  thing  is  accomplished  with  some  makes  of  ma- 
chines by  substituting  the  lower  sprocket  for  the  upper 
sprocket,  and  vice  versa. 

General  Instruction  No.  9. — It  is  highly  important  that  the 
tension  springs  of  your  machine  be  kept  adjusted  exactly 
right.  The  short  piece  of  film  between  the  upper  and  lower 
loop  is  to  all  intents  and  purposes  temporarily  detached 
from  the  rest  of  the  film.  That  is  the  object  of  and  reason 
for  the  upper  and  lower  loops.  They  allow  of  the  strip  of 
film  between  them  being  started  and  stopped  intermittently, 
while  the  rest  of  the  film  runs  continuously.  When  the  in- 
termittent sprocket  acts  it  jerks  this  little  strip  of  film  down 
three-quarters  of  an  inch,  thus  temporarily  lengthening  the 
lower  loop  by  three-quarters  of  an  inch  and  shortening  the 
upper  by  just  that  much.  The  office  of  the  tension  springs 
is  to  stop  this  strip  of  film  when  the  intermittent  sprocket 
stops  and  hold  it  perfectly  still  and  perfectly  flat  over 
the  aperture  during  the  time  the  photograph  is  being 
projected  to  the  screen.  Bearing  this  fact  in  mind,  it  will 
be  seen  that  if  the  tension  springs  be  too  slack  they  will 
not  stop  the  film  (it  moves  at  high  speed  while  the  inter- 
mittent is  in  motion)  exactly  when  the  intermittent  sprocket 
stops.  In  other  words,  the  film  will  "overshoot,"  and,  inas- 
much as  it  will  probably  not  overshoot  exactly  the  same 
amount  every  time,  unsteadiness  of  the  picture  on  the  screen 
will  result.  On  the  other  hand  it  readily  will  be  seen  that, 
while  it  is  absolutely  essential  that  the  tension  springs  be 
tight  enough  to  stop  the  film  when  the  intermittent  stops, 
and  thus  prevent  overshooting,  still,  any  tension  in  excess 
of  this  will  make  the  work  of  the  intermittent  sprocket 
teeth,  of  the  intermittent  movement,  and,  in  fact  the  whole 
mechanism,  just  that  much  harder,  with  the  result  that  there 
will  be  unnecessary  wear  on  the  whole  mechanism  and  the 


464 


MOTION    PICTURE   HANDBOOK 


film  itself.  It  is  a  difficult  matter  and  an  impossibility  to 
adjust  the  tension  so  that  it  will  be  always  exactly  right, 
since  one  piece  of  film  may  be  a  trifle  thicker  than  another, 
or  a  little  bit  smoother,  or  more  oily.  The  operator,  how- 
ever, should  be  very  careful  and  come  as  close  to  the  proper 
adjustment  as  he  possibly  can. 

The  tension  may  be  considered  as  being  approximately  correct 
when  the  picture  is  steady  and  without  movement  on  the  screen 
when  run  at  any  speed  up  to  90  per  minute,  but  at  90  or  there- 
abouts the  picture  begins  to  crawl  up  slightly  on  the  screen. 

Another  fairly  accurate  test  is  to  set  the  tension  so  that 
you  can  just  barely  feel  the  pull  of  the  intermittent  move- 
ment when  the  crank  of  the  mechanism  is  turned  very, 
very  slowly,  and  by  "very,  very  slowly"  I  mean  exactly 
what  I  say — just  barely  moving.  If  you  can  feel  the  jerk 
of  the  tension  appreciably  when  moving  the  crank  thus, 
then  the  tension  is  too  tight.  It  is  a  fact,  however,  that 
it  is  not  always  necessary  to  have  the  tension  tight  enough 
so  that  you  can  feel  it  in  the  crank,  even  when  moved  as 
slowly  as  you  can  move  it.  The  90-foot-per-minute-test  is, 
everything  considered,  the  best  I  know  of. 

General  Instruction  No.  10.— When  running  first  run  films, 
the  emulsion  of  which  is  soft,  there  is  a  decided  tendency 
of  the  emulsion  to  deposit  on  the  tension  springs  or  on  the 
shoes.  This  tendency  is  often  helped  out  by  the  too  liberal 
use  of  cement  in  making  patches.  The  emulsion  and  the 
cement  gather  on  the  polished  surface  of  the  tension  shoe 
in  a  hard,  unyielding  mass,  which,  aside  from  making  the 


Figure  228. 

tension  shoes  jump  and  clatter  is  very  apt  to  injure  the  film, 
and  perhaps  injure  it  seriously  too.  Sometimes  the  excess 
cement  on  the  celluloid  side  will  gather  on  the  aperture  plate 
tracks  also.  When  running  first  run  film  the  tension  springs 
and  aperture  plate  should  be  carefully  examined  after  each 


FOR    MANAGERS    AND    OPERATORS 


465 


reel,  and  any  deposit  found  thereon  should  be  carefully 
cleaned  off  by  using  a  wet  cloth  (water  softens  the  emulsion 
instantly)  or  the  edge  of  a  silver  coin,  or  some  other  soft 
metal. 

Never  use  a  knife  blade,  a  screw  driver  or  other  hard  steel 
instrument  to  scrape  off  the  aperture  tracks  or  tension  shoes; 
by  so  doing  you  will  be  very  likely  to  scratch  the  polished  surface, 
thus  increasing  the  tendency  to  deposit  and  aggravating  the 
trouble. 

The  deposit  of  emulsion  may  be  very  largely  stopped  by 
the  use  of  the  machine  illustrated  in  Fig.  228.  The  illustra- 
tion is,  I  think,  fully  self-explanatory.  The  machine  is  placed 
between  reels  on  the  rewinder,  and  the  film  runs  through  it  in 
rewinding.  The  four  round  objects  are  cylinders  made  of 
wax,  so  set  that  in  the  process  of  rewinding  the  tracks  of 
the  film  bear  on  the  wax  and  receive  a  sufficient  deposit 
of  it  on  both  sides  to  prevent  the  deposit  of  emulsion  or 
cement  on  the  tension  shoes  or  aperture  plate  of  the  projec- 
tor. The  same  thing  may  be  accomplished  by  a  home-made 
affair,  using  large  sperm  or  tallow  candles,  as  per  Fig.  229, 
but  the  machine  in  question  is  cheap  in  price  and  quite 
efficient,  therefore  I  can  advise  its  purchase.  The  mere 
rubbing  of  the  tension  springs  with  the  butt  end  of  a 
tallow  candle  when  threading  the  machine  helps  considerably, 


/ 


\ 


I 


Figure  229. 

though  it  will  not  prevent  deposit.  Another  method  which  is 
fairly  efficient  is  to  hold  a  tallow  candle  lightly  against  the 
teeth  of  the  upper  sprocket  every  half  minute  or  so  when 
running  first  run  films.  This  scrapes  off  a  little  tallow  which 
deposits  on  the  tracks  sufficiently  to  keep  the  tension  springs 
or  shoes  lubricated. 

General  Instruction  No.  11. — It  is  important  that  the  tracks 
of  the   aperture   plate  of  your  projector  be  not  allowed  to 


465  MOTION    PICTURE   HANDBOOK 

become  much  worn.  It  is  absolutely  essential  to  good  re- 
sults on  the  screen  that  the  film  be  held  absolutely  flat  over 
the  aperture  during  the  time  the  picture  is  being  projected, 
and  this  is  not  likely  to  be  done  if  (a)  the  aperture  plate 
tracks  be  appreciably  worn;  (b)  the  shoes  or  springs  do  not 
set  squarely  on  the  tracks,  but  one  or  both  of  them  is 
over  to  one  side.  Worn  aperture  plate  tracks  are  likely  to 
produce  a  buckling  of  the  film,  with  consequent  in  and  out  of 
focus  effect  in  the  center  of  the  picture.  This  is  particularly 
true  of  the  type  of  mechanism  which  employs  a  limber  tension 
spring,  instead  of  a  stiff  tension  shoe.  By  this  I  do  not  wish 
to  be  understood  as  saying  that  in  and  out  of  focus  effect  is 
always  due  to  the  above  causes.  It  may  also  be  due  to  an 
old,  dry,  shrunken  film,  or  ta  too  much  pressure  by  the 
tension  springs. 

General  Instruction  No.  12. — It  is  of  the  utmost  importance 
that  the  sprocket  idlers  be  kept  in  line  with  the  sprocket,  so 
that  each  side  of  the  idler  is  equidistant  from  the  face  of  the 
sprocket,  and  that  the  distance  of  the  idler  from  the  face  of 
the  sprocket  be  two  thicknesses  of  a  film  or  a  trifle  less. 
If  the  sprocket  idlers  be  not  so  set  there  is  likely  to  be 
trouble,  particularly  at  the  lower  sprocket.  Losing  the 
lower  loop  through  the  film  climbing  the  sprocket  teeth  is 
very  often  directly  due  to  the  improper  setting  of  the  idler. 
It  is  either  out  of  line  with  the  sprocket  or  too  close  to  or 
too  far  away  from  the  sprocket.  Many  do  not  realize  the 
importance  of  a  close  adjustment  of  their  sprocket  idlers.  Never 
allow  your  sprocket  idler  to  "ride  the  film" — that  is  to  say,  to 
bear  on  it  with  pressure.  This  is  especially  bad  if  the  pres- 
sure is  greater  on  one  side  than  on  the  other,  and  will  most 
likely  cause  the  film  to  climb  the  sprocket  at  the  first  bad 
patch.  This  does  not  apply  to  the  Edison  machines.  Their 
idler  rollers  ride  directly  on  the  film,  which  is  held  in  place 
by  deep  flanges  at  either  end  of  all  sprockets.  See  to  it  that 
your  sprocket  idlers  turn;  if  they  do  not  they  will  soon  de- 
velop a  flat  spot,  and  sooner  or  later  this  means  trouble. 

General  Instruction  No.  13. — It  is  highly  important  that 
the  intermittent  sprocket  shaft  and  the  cam  or  fly-wheel  shaft 
be  kept  in  exact  alignment  with  each  other.  The  position  of 
the  cam  or  fly-wheel  shaft  is  fixed  and  cannot  be  changed. 
It  will  readily  be  seen  that  if  the  intermittent  sprocket  shaft 
be  out  of  line  with  the  cam  or  fly-wheel  shaft— that  is  to 
say,  if  one  end  of  the  intermittent  sprocket  shaft  be  'high  or 
low  with  relation  to  the  other  end — it  will  bring  one  end  of 
the  intermittent  sprocket  lower  than  the  other  end,  and  the 


FOR    MANAGERS    AND    OPERATORS  467 

teeth  at  the  lower  end  will  be  obliged  to  do  all  the  work  of 
pulling  down  the  film  until  such  time  as  they  have  worn  off 
sufficiently  to  bring  the  teeth  on  the  other  end  into  play, 
whereupon,  if  the  shaft  then  be  lined,  the  opposite  condition 
will  obtain,  and  the  teeth  on  the  other  end  will  be  doing  all 
the  work.  This  would  be  very  hard  on  both  the  film  and 
the  sprocket.  The  method  of  aligning  these  two  shafts  will 
vary  with  different  machines,  and  must  be  left  largely  to  the 
judgment  and  ingenuity  of  the  operator.  In  all  machines  in 
which  the  intermittent  sprocket  shaft  has  a  bearing  at  either 
end  the  adjustment  is  made  by  means  of  two  eccentric  bush- 
ings, and  there  is  always  the  liability,  when  making  an  adjust- 
ment for  the  purpose  of  eliminating  lost  motion  in  the  inter- 
mittent, to  turn  one  bushing  more  than  the  other,  thus  get- 
ting the  sprocket  and  shaft  out  of  level  with  the  cam  shaft. 
In  some  machines  the  distance  between  the  two  shafts  at 
either  end  may  be  tested  with  a  caliper.  With  other  ma- 
chines, however,  this  test  is  of  no  value,  since  the  diameter 
of  one  or  both  the  shafts  is  smaller  at  one  end  than  the 
other.  The  competent  operator,  however,  will  certainly  be 
able  to  devise  some  effective  method  of  testing  this  matter, 
and  he  should  by  all  means  do  so,  since  it  is  of  the  greatest 
importance. 

General  Instruction  No.  14. — On  the  old  type  machines  it  is 
very  important  indeed  that  the  magazines  be  accurately 
lined  with  the  machine.  With  the  newer  projectors  this  is 
taken  care  of  at  the  factory,  and  the  magazines  can  only 
be  placed  in  one  position,  therefore  cannot  possibly  be  out 
of  line.  The  film  in  passing  out  of  the  upper  magazine  and 
into  the  lower  magazine  must  travel  through  the  fire  trap, 
and  if  the  magazine  is  out  of  line  with  the  machine  the  film 
is  likely  to  rub  against  the  side  of  the  trap  and  in  time  cut 
the  metal  in  two,  thus  ruining  the  fire  trap;  also  if  the  upper 
magazine  of  the  old  style  machine  is  much  out  of  line  it  is 
also  quite  possible  the  film  will  not  come  down  squarely  to 
the  upper  sprocket,  and  this  is  likely  to  make  trouble.  If  it 
be  the  lower  magazine  that  is  much  out  of  line  then  the 
take-up  will  pull  the  film  sidewise  and  there  will  be  added 
tendency  to  lose  the  lower  loop.  The  film  should  pass  from 
the  upper  and  into  the  lower  magazine  without  touching 
either  side  of  the  trap. 

General  Instruction  No.  15. — It  is  a  most  excellent  scheme 
to  have  operating  room  reels  and  only  use  the  exchange  reels, 
which  are  very  apt  to  be  in  more  or  less  bad  condition,  in 
the  upper  magazine  for  the  first  run,  placing  one  of  the 


468 


MOTION    PICTURE   HANDBOOK 


house  reels  in  the  lower  magazine  to  receive  the  film.  The 
film  should  thereafter  be  handled  on  the  house  reels  entirely, 
being  rewound  to  the  exchange  reel  only  when  using  for  the 
last  time.  These  house  reels  should  be  kept,  in  first  class 
condition,  with  the  spring  clip  carefully  adjusted.  Better 
still,  make  a  slot  through  the  wooden  hub  and  dispense  with 
the  spring  clip  entirely.  It  is  aggravating  for  the  operator 
who  has  to  do  rapid  work  in  threading  up  to  be  obliged  to 
work  with  a  reel  which  is  in  bad  condition.  The  only  way 
to  avoid  this  with  any  degree  of  certainty  is  by  a  theatre 
owning  reels  of  its  own.  There  is  a  most  excellent  reel 
spring  made  by  Chas.  F.  Woods,  Princeton,  Ind.,  known  as 
the  "Woods  Improved  Film  Clip,"  with  which  operators  will 

do   well   to   equip   their 

house  reels.  The  con- 
struction and  operation 
of  this  little  device  is 
clearly  shown  in  Fig. 
230. 

General  Instruction 
No.  16. — In  most  pro- 
jection machines  there 
is  some  sort  of  tension 
device  in  the  upper 
magazine,  designed  to 
prevent  the  reel  from 
revolving  too  freely, 
and  it  is  important  that 
(a)  this  tension  device 
be  so  designed  that  it 
will  not  and  cannot 
catch  on  loose  screws 
on  reel  hubs;  (b)  that  the  tension  be  sufficient  to  just  barely 
keep  the  film  taut  at  all  times,  and  stop  the  reels  instantly 
wihen  the  projector  is  stopped.  The  importance  of  this  is 
seen  when  we  consider  that,  if  the  reel  revolves  too  freely, 
and  the  machine  be  stopped  when  the  upper  reel  is  three- 
fourths  or  more  empty,  and  the  reel  continues  to  revolve, 
thus  unwinding  more  or  less  slack  film,  when  the  machine  is 
started  it  is  likely  to  get  up  to  normal  speed  before  it  takes 
up  all  the  slack,  and  then  the  reel  must  be  started  instantly 
at  full  speed.  As  a  result  there  is  a  heavy  jerk,  which  may 
pull  patches  in  two,  rip  out  sprocket  holes,  or  even  pull  the 
film  itself  in  two. 

General  Instruction  No.  17.— It  is  sometimes  desirable  that 


Figure  230. 


FOR    MANAGERS    AND    OPERATORS  469 

the  form  of  the  aperture  be  changed  in  order  to  eliminate 
the  keystone  effect  due  to  a  steep  pitch  in  the  projection  or 
the  keystone  effect  due  to  a  side  throw.  This  may  be  ac- 
complished by  taking  off  the  aperture  plate,  filling  in  the 
same  with  solder  for  one-sixteenth  or  one-eighth  of  an 
inch  at  either  side,  or  if  it  be  a  side  keystone  effect,  then  at 
the  top  and  bottom.  Having  completed  this  part  of  the  job, 
put  the  aperture  back  in  place,  and,  with  the  light  projected 
to  the  screen,  using  a  small,  fine,  flat  file,  carefully  file  the 
sides  until  the  light  on  the  screen  is  perpendicular  on  the 
sides  or  horizontal  on  top  and  bottom  if  it  be  keystone 
effect.  Do  your  filing  slowly  and  carefully.  It  is  well  to 
hang  lines  at  the  sides  of  the  screen  to  guide  you  in  your 
work.  Attach  top  of  line  (narrow,  black  tape  is  good)  to 
screen,  just  at  bottom  of  top  corner  bend  and  attach  weight 
to  its  lower  end  so  it  will  hang  perfectly  straight  and  per- 
pendicular. 

THE  REVOLVING  SHUTTER 

General  Instruction  No.  18. — It  is  of  the  utmost  importance 
that  the  operator  have  a  comprehensive  and  complete  knowl- 
edge of  the  principles  involved  in  and  the  optical  action  of 
the  revolving  shutter.  The  revolving  shutter  of  a  projection 
machine  serves  a  certain  definite  purpose,  viz: 

It  shuts  off  the  light  from  the  screen  during  the  time  each 
individual  picture  is  being  moved  down  to  make  room  for  the 
next,  and  turns  it  on  again  ivhile  the  picture  is  being  projected 
to  the  screen. 

Remember  there  is  really  no  such  thing  as  a  "moving 
picture."  What  we  term  "moving  pictures"  are  in  reality  a 
blending  or  dissolving  of  snapshot  photographs,  taken  at  the 
rate  of  about  sixteen  to  the  second,  into  each  other  at  ap- 
proximately the  same  rate  of  speed  at  which  they  were 
taken. 

Examine  your  film;  measure  off  one  foot  of  it  and  you 
will  find  thereon  precisely  sixteen  complete  pictures,  which 
are  nothing  more  or  less  than  snapshot  photographs  taken 
at  the  rate  of  approximately  sixteen  to  the  second.  These 
photographs  are  strung  out,  one  after  the  other,  on  strips  of 
celluloid  of  varying  length,  several  lengths  being  joined 
together  into  a  total  length  of  one  thousand  feet,  which  is  the 
ordinary  length  of  a  "reel  of  film."  As  the  film  passes  through 
the  projector  these  photographs  are  successively  displayed,  in 
an  inverted  position  (upside  down),  in  front  of  the  machine 
aperture,  and  are  projected,  one  after  the  other,  to  the 


470  MOTION    PICTURE   HANDBOOK 

screen.  In  order  to  accomplish  this 'the  photographs  must 
each  one  be  standing  perfectly  still,  and  lie  perfectly  flat 
over  the  aperture  during  the  period  of  projection.  The  in- 
termittent movement  of  the  machine  is  for  the  purpose  of 
pulling  each  successive  photograph  away  from  over  the  ma- 
chine aperture  and  replacing  it  with  the  next  succeeding 
picture,  or,  in  other  words,  moving  the  film  down  exactly 
three-fourths  of  an  inch,  stopping  it  dead  still  while  the  pic- 
ture is  being  projected  to  the  screen,  and  then  jerking  it 
down  again,  and  so  on  throughout  the  full  length  of  the 
reel  of  film.  As  a  matter  of  fact,  at  ordinary  speed,  each 
picture  occupies  one-sixteenth  of  a  second  from  the  time  it 
begins  to  move  until  the  next  picture  begins  to  move,  about 
one-sixth  of  this  time  being  consumed  in  the  actual  move- 
ment of  the  film  and  five-sixths  in  the  projection  of  the 
picture.  And  right  here  the  office  of  the  revolving  shutter 
comes  in.  If  you  have  an  outside  shutter  machine,  slip  the 
shutter  off  its  spindle  and  project  a  few  feet  of  film.  You 
will  find  that  the  picture  will  be  projected,  and  that  the  light 
will  be  far  more  brilliant  than  it  was  with  the  shutter  in 
place.  You  will  find,  however,  that  from  every  white  object  in 
the  film  there  will  be  a  streak  of  white,  which  apparently 
goes  both  up  and  down  from  the  object,  but  in  reality  goes 
down  only,  the  other  end  being  the  effect  of  a  similar  white 
object  in  the  next  picture.  The  net  result  is  streaks  of  white 
across  the  picture.  This  is  what  is  called  "travel  ghost." 
It  is  due  to  the  fact  that  as  the  picture  is  jerked  down,  to 
make  way  for  the  next  one,  the  effect  of  impression  of  any 
white  object  therein  on  the  retina  of  the  eye  is  greater  than 
the  effect  of  impression  of  the  surrounding  dark  objects  in 
the  film.  Hence  as  the  picture  is  moved  down  we  see  white 
moving  across  the  space  formerly  occupied  by  the  darker 
object  in  the  picture.  In  other  words,  the  eye  follows  the 
white  object  as  it  moves  across  the  aperture,  but  it  does 
not  see  the  dark  object,  or  at  least  does  not  see  it  so 
plainly.  Owing  to  this  effect  it  is  necessary  to  shut  off  the 
light  from  the  screen  during  the  time  the  film  is  in  motion, 
and  that  is  the  duty  the  revolving  shutter  performs. 

Without  any  film  in  your  machine,  open  the  gate,  project  the 
white  light  to  the  screen,  and  run  the  projector  very  slowly.  You 
will  observe  that  the  revolving  shutter  shuts  off  all  the  light 
from  the  screen  every  time  one  of  its  blades  comes  in  front 
of  the  lens;  hence  two  or  three  (according  to  whether  your 
machine  has  a  two  or  three  wing  shutter)  times  during  the 
period  a  picture  is  being  exposed  and  projected  the  light  is 


FOR   MANAGERS   AND   OPERATORS  471 

entirely  cut  off  from  the  screen.  In  actual  projection  we 
therefore  have,  in  effect,  a  succession  of  flashes  of  brilliant 
light  and  total  darkness,  but  when  the  machine  is  run  at 
normal  speed,  with  a  properly  designed  shutter,  these  flashes 
of  light  and  darkness  alternate  so  rapidly  that  either  the  eye 
does  not  catch  the  effect  at  all  or  catches  it  but  slightly.  So 
far  as  our  eye  is  concerned  the  illumination  of  the  screen  is 
continuous,  though  of  diminished  brilliancy. 

No  matter  how  many  blades  your  shutter  may  have,  only 
one,  the  wide  or  main  blade,  has  anything  whatever  to  do 
with  the  actual  shutting  off  of  the  light  during  the  time  the 
picture  is  being  moved  down  to  make  way  for  the  next.  As 
the  intermittent  sprocket  starts  to  move  the  wide  blade  of 
the  shutter  comes  in  front  of  the  lens  (that  is  what  is  meant 
by  "timing  the  shutter" — setting  it  in  such  relation  to  the 
intermittent  movement  that  it  will  cut  off  the  light  from 
the  screen  as  the  intermittent  begins  to  move,  and  turn  it 
on  again  just  as  the  movement  ceases)  and  shuts  off  the 
light  from  the  screen  while  the  intermittent  sprocket  is  mov- 
ing and  pulling  the  next  picture  down  over  the  aperture.  As 
the  intermittent  sprocket  comes  to  rest  the  wide  blade  of  the 
shutter  passes  from  in  front  of  the  lens,  thus  allowing  the 
picture  to  be  projected  to  the  screen. 

From  this  it  is  seen  that,  in  theory,  the  shutter  must  be  so 
set  that  it  will  cover  the  aperture,  or  lens,  at  the  exact  in- 
stant the  intermittent  begins  to  move,  and  uncover  it  at  the 
exact  instant  the  intermittent  sprocket  comes  to  rest.  That 
is  the  theory.  In  practice,  however,  it  has  been  found  that 
this  may  be  modified  to  some  extent,  and,  as  a  matter  of 
fact,  with  most  machines,  the  lens  is  only  about  three-fourths 
closed  when  the  intermittent  sprocket  begins  to  move,  and 
is  still  slightly  open  when  the  movement  ceases.  If,  how- 
ever, the  leeway  be  just  a  little  bit  too  much  there  will  be 
travel  ghost. 

All  this  has  to. do  with  the  wide  blade  of  the  shutter.  All 
shutters,  however,  have  two  or  three  wings,  but  these  extra 
wings  have  nothing  whatever  to  do  with  cutting  off  the  light 
during  the  time  the  film  is  moving.  But  while  this  is  true 
they  are,  nevertheless,  of  the  utmost  importance.  As  already 
has  been  explained,  in  projection  the  screen  is  alternately 
brilliantly  lighted  and  totally  dark.  Now  the  human  eye  is 
a  peculiar  instrument.  It  will  transmit  to  the  brain  a  certain 
number  of  separate  impressions  per  second,  as  separate  im- 
pressions, but  beyond  that  number  the  impressions  become 
merged  into  each  other  so  that  the  effect  is  that  of  con- 


472  MOTION    PICTURE   HANDBOOK 

tinuity.  This  is  what  is  called  "persistence  of  vision,"  and  it 
is  this  peculiarity  of  the  eye  which  makes  "moving  pictures" 
possible.  So  far  as  the  shutter  be  concerned,  persistence  of 
vision  acts  as  follows:  If  the  flashes  of  light  and  darkness 
come  too  far  apart,  or  are  disproportionate  to  one  another, 
then  the  eye  will  perceive  the  difference.  Under  this  condi- 
tion persistence  of  vision  operates  incompletely,  and  instead 
of  an  illusion  of  perfectly  steady  illumination  the  rapidly 
recurring  flashes  of  darkness  will  be  perceptible  in  the  shape 
of  what  is  termed  "flicker."  This  flicker  is  a  very  serious 
matter  indeed,  since  it  causes  eye  strain  exactly  in  propor- 
tion to  its  amount.  If  excessive  it  is  highly  injurious  to  the 
eyes.  It  has  been  found  that  if  the  flashes  of  light  and 
darkness  be  equal  to  each  other  and  at  the  rate  of  forty-eight 
or  more  of  each  to  the  second,  the  effect  will  be,  to  all 
intents  and  purposes,  that  of  continuous  illumination,  without 
any  perceptible  flicker  at  all,  when  not  very  brilliant  illumina- 
tion is  used.  With  more  brilliant  illumination,  such  as  is  now 
used  in  up-to-date  theatres,  this  must  be  increased  to  about 
55.  Therefore  this  is  the  condition  machine  manufacturers 
are  striving  to  attain,  or  should  strive  to  attain.  But  in 
order  to  attain  this  there  must  be  a  three-wing  shutter,  with 
all  three  blades  of  the  same  width,  and  three  light  openings 
each  of  equal  width  with  the  blades. 

This  might  seem  to  the  uninitiated  a  simple  condition  to 
accomplish,  but,  as  a  matter  of  fact,  it  is  not.  It  brings  up 
some  very  difficult  problems.  First,  as  has  already  been 
pointed  out,  the  main  blade  of  the  shutter  must  be  wide  enough 
to  cover  about  three-fourths  of  the  aperture,  or  light  beam, 
when  the  intermittent  sprocket  starts  to  move  and  still  have 
about  the  same  amount  covered  when  it  comes  to  rest.  This 
fixes  the  minimum  width  of  the  main  blades  arbitrarily.  It 
also  means  that 

The  more  rapid  the  intermittent  movement,  the  less  width 
the  main  shutter  blade  need  have, 

and  with  a  1  to  6  movement,  provided  there  be  no  lost  motion 
between  the  revolving  shutter  and  the  intermittent,  a  con- 
dition is  approached  where  the  outside  shutter  may  have 
three  wings,  each  wing  of  equal  width  with  the  other  wings 
and  'he  light  openings.  This  is,  I  believe,  the  best  condition 
obtainable,  and  I  am  of  the  opinion  that  it  will  e  the  best 
so  long  as  intermittent  projection  machines  are  usad. 

It  is,  however,  not  always  possible  to  attain  this  condition, 
since  it  presumes  the  light  ray  to  be  cut  at  the  narrowest 
possible  point,  and  with  very  short  focal  length  lenses  the 


FOR    MANAGERS    AND    OPERATORS  473 

light  ray  spreads  so  rapidly  that  with  lenses  and  projection 
machines  as  at  present  made  the  shutter  can  only  cut  the 
beam  after  it  has  spread  too  much  to  allow  of  the  ideal 
condition,  before  described,  being  attained.  With  very  short 
focal  length  lenses  the  beam  is  so  wide  that  the  main  shutter 
blade  must  have  abnormal  width  in  order  to  eliminate  travel 
ghost,  and  this  throws  the  shutter  out  of  proportion  and 
makes  for  flicker  when  the  machine  is  run  at  normal  speed. 

Where  60  cycle  A.  C.  is  used,  however,  the  use  of  the 
three-wing  shutter  brings  in  another  equation,  60  cycle  A.  C. 
reverses  its  direction  120  times  per  second,  or  7200  times  per 
minute.  With  a  three-wing  shutter  projection  machine  run- 
ning at  the  rate  of  60  feet  of  film  per  minute,  normal  speed, 
the  light  is  cut  2880  times  a  minute.  Now  one-half  of  the 
alternations  of  60  cycle  A.  C.  would  be  3600,  and  if  the  cur- 
rent happened  to  be  not  quite  60,  but,  say,  instead,  56  or  58, 
just  a  little  of  overspeeding  of  the  machine  would  bring  the 
wings  of  the  shutter  into  synchronism  with  one  side  of  the 
alternations.  Under  these  conditions  if  the  wings  happen  to 
cut  the  light  just  at  the  period  of  its  greatest  brilliancy  (See 
Page  16,  Fig.  4)  its  power  would  be  diminished  by  approx- 
imately one-half.  As  a  matter  of  fact,  however,  this  very 
thing  often  does  occur  where  a  three-wing  shutter  is  used 
with  60  cycle  A.  C.,  and  the  net  result  is  a  waving  effect  of 
the  light;  that  is  to  say,  its  brightness  will  alternately 
diminish  and  increase,  the  alternations  of  effect  being  due 
to  the  fact  that  the  shutter  blades  are  not  likely  to  stay  in 
exact  synchronism  with  the  alternations  for  more  than  one 
or  two  seconds  at  a  time.  For  this  reason  it  is  advised  that 
a  two-wing  shutter  be  used  with  60  cycle  alternating  current. 
The  two-wing  shutter,  as  a  rule,  gives  somewhat  more  light 
than  the  three-wing  shutter,  and  is  therefore  favored  by 
some  managers  who  prefer  to  have  flicker  rather  than  cur- 
rent bills.  The  use  of  the  two-wing  shutter,  however,  is  not 
to  be  advised  except  with  60  cycle  A.  C.,  or  with  gas  or 
other  weak  illuminant. 

In  this  connection  let  me  say  that  the  tendency  to  flicker  in- 
creases with  the  brilliancy  of  the  projection  and  with  increase  of 
size  of  picture,  and  conversely  diminishes  with  decreased  brilliancy 
of  projection  and  decrease  in  size  of  picture. 

All  this  has  been  explained  at  considerable  length  in  order 
to  give  the  operator  as  clear  an  understanding  as  may  be 
had  of  the  points  involved,  but  in  addition  to  the  foregoing 
there  is  still  another  exceedingly  important  point  which 
should  receive  due  consideration. 


474  MOTION    PICTURE   HANDBOOK 

Almost  all  the  later  models  of  projectors  are  equipped 
with  an  "outside  shutter."  Where  the  outside  shutter  is  used 
another  point  of  much  importance  is  involved,  viz:  width  of 
the  light  beam  at  the  point  the  shutter  cuts  it,  or,  in  other 
words,  the  position  of  the  shutter  as  regards  its  distance  from 
the  lens. 

In  Fig.  63A,  Page  145,  the  method  of  determining  proper 
location  for  the  shutter  is  shown.  Place  a  piece  of  metal  with 
a  hole,  say,  one-quarter  inch  in  diameter  against  the  conden- 
ser so  that  the  hole  will  come  approximately  in  the  center 
of  the  condensing  lens.  Now  open  machine  gate,  project 
the  light  through  this  hole  to  the  screen.  Blow  a  little 
smoke  on  a  ray  just  in  front  of  the  lens  and  you  will  find  the 
ray  to  appear  as  in  Fig.  63A,  though  the  thinnest  point  may 
be  inside  the  lens  barrel  if  the  lens  be  of  short  focal  length. 
The  correct  position  for  your  shutter  is  at  the  thin  point  of 
the  ray,  provided  you  can  get  it  there,  but  this  does  not 
apply  to  either  very  short  focal  length  lenses  or  very  long 
focal  length  lenses.  In  fact,  it  only  applies  to  lenses  between, 
say,  Zl/2  and  4  inches,  and  about  5y2  and  6  inches  e.  f.  When 
the  lens  is  in  the  right  position  the  correct  position  for  the 
shutter  may  also  be  determined  by  watching  it  cut  off  the 
light  on  the  screen  when  revolved  very  slowly.  //  the  shadow  is 
moving  in  a  contrary  direction  to  the  movement  of  the  shutter, 
the  shutter  should  be  moved  toward  the  screen;  if  the  shadow 
moves  in  the  same  direction  as  the  shutter  the  shutter  is  too  far 
from  the  lens.  When  it  is  in  correct  position  the  effect  on  the 
screen  is  a  dissolving  effect,  the  shadow  entering  the  screen  both 
from  above  and  below.  When  the  shutter  is  in  correct  position 
the  periods  of  absolute  darkness  may  be  considerably  shorter 
than  the  periods  of  absolute  brightness  when  using  a  50  per  cent, 
two-blade  shutter.  Therefore,  there  is  actually  a  gain  in  light  by 
having  the  shutter  in  the  right  position,  and  this  gain  is  equal 
to  twice  the  diameter  of  the  light  beam,  there  being  four 
edges  on  a  two  blade  shutter,  and  as  the  light  decreases  or 
increases  while  being  cut  from  full  to  zero  the  gain  on  each 
edge  is  equal  to  one-half  of  the  diameter  of  the  beam,  the 
result  of  the  comparatively  gradual  change  from  light  to 
darkness  should  result  in  a  softer  tone  and  diminution  of 
flicker  effect. 

The  width  of  the  shutter  blade  may  be  tested  by  observ- 
ing whether  or  not  any  part  of  the  bright  spot  of  light  leaves 
the  shutter  during  the  movement  of  the  intermittent  sprocket. 
If  it  does  this  on  one  side  then  the  shutter  is  not  set  right; 


FOR  MANAGERS  AND  OPERATORS 


475 


if  it  does  it  on  both  sides  the  shutter  blade  is  too  narrow 
and  there  will  be  a  tendency  to  travel  ghost.  If,  when  the 
intermittent  sprocket  stops,  the  edge  of  the  bright  spot  has 
not  reached  the  edge  of  the  shutter,  then  the  main  blade  is 
unnecessarily  wide  and  there  is  light  loss.  The  intelligent 
application  of  this  method  will  show  at  a  glance  exactly 
wherein  the  main  shutter  blade  lacks  in  being  adapted  to  local 
conditions. 

The  reason  why  an  outside  shutter  of  large  diameter  can 
be  better  proportioned  than  can  an  inside  shutter  of  small 
diameter  is  illustrated  at 
Fig.  231,  which  will  con- 
vey an  accurate  idea  of  the 
effective  difference  in  shut- 
ters of  small  diameter  and 
others  of  larger  diameter. 
In  the  sketch  "X,"  the 
aperture  opening,  is  eleven- 
sixteenths  by  fifteen-six- 
teenths of  an  inch.  With 
the  small,  inside  shutter 
illustrated  by  the  smaller 
circle  c  b  a,  the  lines  a  b 
indicate  the  width  of  shut- 
ter blade  necessary  to 

cover  opening  X,  without  providing  for  its  being  covered 
during  the  time  the  film  is  in  motion.  Lines  a  c  indicate  the 
additional  width  of  shutter  blade  necessary  to  provide  for 
covering  opening  X  during  the  travel  of  the  film. 

You  will  thus  see  that  with  a  shutter  of  small  diameter  a 
blade  of  great  width,  as  compared  to  the  total  circle,  is  es- 
sential if  opening  X  is  to  be  covered  during  the  entire  time 
the  film  is  in  motion.  This  is  primarily  because  of  the 
excessive  width  of  blade  required  to  cover  the  aperture  in  the 
first  place. 

It  is  not  difficult  to  see  that,  under  these  conditions,  it 
would  be  impossible  to  add  more  than  one  other  blade  to 
such  a  shutter,  and  even  that  blade  could  not  be  of  very 
substantial  width  unless  a  very  large  percentage  of  the  total 
light  be  cut.  In  practice,  however,  the  inside  shutter  is  not, 
of  course,  of  such  extremely  small  diameter  as  shown,  but 
it  is  nevertheless  too  small  to  admit  of  using  three  blades  of 
anything  like  equal  width,  as  is  necessary  if  three  are  to  be 
used  and  the  flicker  reduced  to  a  minimum. 


Figure  231. 


476  MOTION    PICTURE    HANDBOOK 

On  the  other  hand,  take  a  shutter  of  the  outside  type, 
having  a  radius  as  indicated  by  1-2  and  1-3  (radius  means  one- 
half  the  diameter  of  a  circle),  and  it  will  be  observed  that 
lines  A  B  form  a  blade  covering  aperture  X,  whereas  lines 
B  C  form  a  blade  capable  of  covering  opening  X  during  the 
entire  movement  of  the  film.  You  will  observe,  too,  that 
this  blade,  instead  of  occupying  more  than  half  the  circle, 
actually  covers  but  a  trifle  more  than  one-sixth  of  it.  We 
will  thus  be  enabled  to  add  two  more  blades  of  substantial 
width,  and  still  cut  no  more  light  than  would  the  smaller 
shutter  having  but  one  or  two  blades. 

Fig.  231  contains  the  meat  of  the  w.hole  shutter  matter 
as  applied  to  the  relative  merits  of  inside  and  outside  shutters, 
It  all  sums  up  in  the  fact  that  a  shutter  of  very  much  larger 
diameter  may  be  used  outside,  thus  allowing  of  a  better  ar- 
rangement of  "flicker  blades."  Added  circumferential  or 
peripheral  speed  also  helps  a  little. 

General  Instruction  No.  19. — A  strongly  magnetized  screw- 
driver is  an  excellent  operating  room  tool.  Small  machine 
screws  may  then  be  removed  or  inserted  without  danger  of 
dropping  them,  with  resultant  vexation  and  trouble. 

General  Instruction  No.  20. — The  standard  aperture  now  in 
use  is  .6796  inch  high  by  .9062  inch  wide. 

INSTRUCTIONS  FOR  VARIOUS  MECHANISMS 

The  instructions  for  the  various  mechanisms  are  intended 
to  enable  the  operator  to  perform  any  operation  which  may 
at  any  time  be  necessary.  By  means  of  the  photographs  and 
system  of  numbering  the  parts,  it  is  hoped  and  believed  that 
the  method  of  removing  and  replacing  or  adjusting  various 
parts  of  the  machine  will  be  made  so  plain  and  simple  that 
even  the  inexperienced  man  will  .have  little  trouble  in  under- 
standing and  following  the  instructions,  whereas  the  ex- 
perienced operator  will  be  greatly  aided  when  called  upon  to 
take  charge  of  a  mechanism  which  is  new  to  him. 

At  first  glance  the  various  instructions  may  seem  somewhat 
complicated.  They  are,  in  fact,  very  simple  and  easily  fol- 
lowed. In  this  connection  it  must  be  remembered  that  the 
operator  seldom  has  occasion  to  use  more  than  one  of  the 
instructions  at  a  time,  while  some  of  them  will  be  used  very 
rarely  and  perhaps  not  at  all. 

The  numbers  refer  to  parts  and  plates,  thus:  678,  P.  7,  means 
that  part  678  will  be  found  on  Plate  7;  682,  P.  3  and  5,  means 
that  part  682  will  be  found  on  both  Plates  3  and  5. 

Instructions   for   the   leading  makes   of   machines   will   be 


FOR    MANAGERS    AND    OPERATORS 


477 


found  on  the  following  pages:  Edison  Super-Kinetoscope, 
477;  Power's  Cameragraph,  491;  The  Simplex,  513;  The 
Motiograph,  528;  The  Standard,  566;  The  Baird,  546,  and  the 
Edison  Model  D,  579. 

Edison  Super-Kinetoscope 


51  z 


Figure  232. 

Important  Notice. — The  Super-Kinetoscope  table  rods  only 
allow  about  18  inches  from  apex  of  front  condenser  lens  to 
film.  Where  this  will  not  allow  the  matching  of  lens  system 
as  in  table  1,  Page  141,  the  Edison  company  will,  without 
charge,  exchange  these  rods  for  special  longer  ones. 

IN  the  following  instructions  only  directions  for  disassem- 
bling the  various  parts  of  the  mechanism  are  given,  it  being 
intended  that  the  operator  carefully  study  the  situation  be- 
fore he  starts  taking  the  parts  off  and  that  he  closely  watch 
the  disassembling  and  reassemble  by  reversing  that  process. 


478  MOTION    PICTURE   HANDBOOK 

No.  1. — To  remove  the  casing  from  the  Super-Kinetoscope, 
first  open  both  doors  and  at  the  top  hinge  corner  will  be 
found  a  stop.  Release  the  stops  on  both  doors  by  taking 
out  the  screw  which  fastens  them  to  the  door  casing.  Next 
remove  screws  26245  (four  of  them)  P.  1,  and  take  off  the 
revolving  shutter  casting,  then  remove  nine  round  head 
screws  in  the  front  plate  (lens  end),  which  will  release  the 
entire  front  plate  and  the  two  doors.  You  may  then  take 
off  the  back  plate  by  releasing  the  set  screw  in  knob  26205,  P. 
1,  and  removing  three  round  head  screws  at  the  top  and  three 
at  the  bottom.  In  replacing  the  mechanism  on  its  base,  first, 
before  you  set  it  down  on  the  base,  pull  the  automatic  stop 
26131,  P.  3,  back  so  that  it  stands  straight  up,  also  guide 
vertical  shaft  so  that  the  screwdriver-shaped  end  enters  take- 
up  friction  disc  slot.  If  you  don't  do  this  the  contact  pin 
which  sets  down  in  a  slot  in  the  casting  is  likely  to  strike 
and  become  injured.  There  are  two  dowel  pins  in  the  base. 
Set  down  the  mechanism  so  that  it  enters  the  pins. 

No.  2. — The  mechanism  is  released  from  base  casting  26290, 
P.  4,  by  removing  hexagon  head  screws  (three  of  them) 
26019. 

No.  3. — Balance  wheel  26184,  P.  4,  may  be  removed  as  fol- 
lows :  With  a  large  screwdriver  remove  screw  26186,  P.  4.  In  the 
face  of  the  wheel  hub  will  be  seen  a  slot.  Set  this  slot  straight  up 
and  down  and  with  the  point  of  the  screwdriver  tap  sharply 
on  the  top  edge  of  what  appears  to  be  an  offset  in  the  casting 
of  the  wheel  but  what  is  really  a  key  washer.  A  sharp  blow 
will  displace  this  washer,  whereupon,  holding)  gear  wheel 
26277,  P.  4,  stationary,  pull  the  balance  wheel  off  the  spindle 
with  a  twisting  motion.  The  reassembling  is  but  a  reversal 
•of  the  foregoing  process,  but  be  sure  to  get  the  key  washer 
properly  located  in  its  slot. 

No.  4.— To  remove  gear  26277,  P.  4,  follow  Instruction  No. 
3  and  remove  hexagon  nut  20622,  P.  3,  and  tap  lightly  on  the  end 
of  the  bolt,  the  head  of  which  is  shown  at  26042,  P.  4.  Hav- 
ing removed  the  bolt,  the  gear  may  be  taken  away,  carrying 
with  it  pinion  26277,  P.  2.  This  pinion  may  be  removed  from 
the  large  gear  and  replaced,  but  the  job  can  only  be  done  at 
the  Edison  factory.  Don't  try  to  have  your  local  machinist 
do  it  unless  you  are  looking  for  trouble. 

No.  5. — To  remove  gear  26031,  P.  4,  follow  instructions  Nos.  3 
and  4  and,  holding  the  gear  stationary  with  a  large  screw- 
driver, remove  screw  26033,  P.  4,  and,  using  a  hard  wood  or 
copper  punch,  drive  the  shaft  out.  In  the  end  of  the  shaft 
will  be  found  a  key.  Be  careful  and  don't  lose  it;  also  don't 


FOR   MANAGERS   AND   OPERATORS  479 

fail  to  get  it  back  in  place  in  the  assembly.     This  shaft  is 
the  main  driving  or  crank  shaft. 


36459-  - 


26191— 
26025  — 


26564 
26566 
26578 ' 


Plate  1,  Figure  233. 

No.  6. — The  main  crankshaft  to  which  crank  26690,  P.  3,  is 
attached  is  removed  by  following  Instruction  No.  5. 

No.  7.— Gear  26045,  P.  4,  is  held  to  its  shaft  by  a  set  screw 
in  its  hub  and  is  located  circumferentially  on  its  shaft  by  a 
key.  To  remove  the  gear  loosen  the  set  screw  and  pull  the 
gear  off,  being  careful  not  to  lose  the  key  and  to  get  it 
properly  located  in  reassembling. 


480 


MOTION    PICTURE    HANDBOOK 


No.  8. — Gear  26191,  P.  3,  is  held  to  its  shaft  by  a  set  screw 
in  its  hub  which  bears  on  a  key  bending  into  a  key  way  in  its 
shaft  and  gear.  The  gear  may  be  removed  by  releasing  this  set 
screw  and  pulling  outward  on  gear  26045,  P.  4,  tapping,  if 
necessary  on  the  inner  end  of  the  shaft  with  a  small  copper 
or  hard  wood  punch. 


2649 


i  i 
261  I 
2620 
26!0 
26110 
261  li 
26135 
26968 
26068 
26164 


Plate  2,  Figure  234. 


No.  9. — To  remove  lens  carrier  26194,  P.  3,  loosen  set  screw 
1714  and  another  one  similarly  located  at  the  other  end  of 
the  shaft  and  two  similar  set  screws  in  the  casting  at  the 
end  of  shaft  26201,  P.  1,  which  supports  the  casting.  Next 
remove  gear  26270,  P.  1,  by  loosening  set  screw  in  the  cast- 


FOR    MANAGERS    AND    OPERATORS  481 

ing  opposite  the  inner  end  of  its  spindle  and  pulling  the  gear 
out.  You  may  then,  using  a  hard  wood  or  copper  punch, 
drive  rods  26202  and  26201  inward,  toward  the  operating  end 
of  the  machine  (until  casting  26194,  P.  3,  is  released).  The 
reassembling  is  but  a  reversal  of  the  process  of  disassem- 
bling, but  in  working  with  parts  of  this  kind  remember  they 
are  fitted  closely  and  if  they  move  a  little  bit  hard  don't  go 
at  things  with  a  ten-pound  hammer,  but  have  a  little  patience 
and  keep  tapping  until  the  part  is  released. 

No.  10. — To  remove  shaft  26069,  loosen  screws  (two  of 
them)  26966,  P.  4,  in  the  collar  next  to  the  governor  and  one 
screw  in  the  hub  of  the  governor.  Next  loosen  pin  screw 
26049  in  the  hub  .of  gear  26067,  P.  3,  and  then,  holding  the 
governor  and)  its  collar  stationary,  pull  the  shaft  out.  It 
may  be  found  that  the  gears  and  collar  of  this  shaft  will  stick 
somewhat  and  you  will  have  to  use  a  little  force  in  starting 
the  shaft  out. 

No.  11. — To  remove  the  automatic  governor  and  fire  shutter 
26207,  P.  3,  loosen  screw  in  the  hub  of  governor.  Next  re- 
move screw  26073  and  another  similar  screw  in  the  lower  end 
of  part  26061,  P.  2,  which  releases  the  entire  governor  and 
plate  which  may  be  pulled  straight  out  off  the  shaft.  It  is 
not  deemed  expedient  to  disassemble  the  automatic  governor 
itself.  It  is  exceedingly  unlikely  that  anything  will  go  wrong 
with  its  internal  arrangement,  but  if  it  does  then  the  governor 
must  be  sent  to  the  Edison  factory  for  repairs. 

No.  12. — To  remove  upper  sprocket  26071,  P.  1,  screw  out 
part  26074  and  afterward  you  can  pull  off  the  sprocket. 

Caution:  Screw  26078,  P.  3,  carries  a  coil  spring.  When 
you  remove  the  screw  look  out  that  you  don't  lose  the  spring. 

Caution:  Between  the  upper  sprocket  and  the  casting  is 
a  collar  with  2  set  screws  which  holds  upper  sprocket  shaft 
in  position.  On  reassembling  don't  fail  to  get  this  collar 
in  place,  or  you  will  be  unable  to  work  the  sprocket  for  set- 
ting the  upper  loop. 

No.  13.— To  remove  gear  26025,  P.  4,  loosen  the  set  screw 
in  its  hub  and  pull  the  shaft  and  upper  sprocket  out  on  the 
sprocket  side.  If  the  shaft  starts  hard,  use  a  copper  punch 
to  drive  it  out. 

Caution:  Between  the  upper  sprocket  and  the  casting  is  a 
collar.  In  reassembling  don't  fail  to  get  this  collar  in 
place. 


482 


MOTION    PICTURE   HANDBOOK 


No.  14. — The  upper  sprocket  idler  bracket  26082,  P.  3,  and 
its  spindle  may  be  released  by  taking  out  a  small  set  screw 
in  the  face  of  the  bracket. 

Note. — This  may  never  be  necessary,  as  roller  ends  can  be 
removed  when  worn  without  taking  the  bracket  off. 


26292     26496 


26126 
26127 

26S06 
26105 
26107 

26153 
5705 
1714 

26H)3 
26194 
2606? 
26195 
26049 
26069 
26196 
26103 
26107 


7712      26252     \  26292 
26945         2629! 


Plate  3,  Figure  235. 


No.  15. — There  are  two  short  shafts  at  either  end  of  the 
casting,  carrying  a  hardened  double  flanged  roller.  Either 
one  may  be  removed  independent  of  the  other  by  loosening 
the  set  screw  in  the  face  of  the  bracket  casting.  The  upper 
flange  of  these  rollers  rides  on  the  sprocket.  There  is  no 
way  of  adjusting  their  distance  from  the  sprocket.  There- 


FOR    MANAGERS    AND    OPERATORS 


483 


fore  it  is  highly  important  that  the  tension  supplied  by  the 
coil  spring  26089,  P.  2  (three  of  them),  be  neither  too  heavy 
nor  too  light.  No  explicit  directions  can  be  given  except 


-26025 
—26025 


26019 

— 26153 

26567 
26570 
26 
26 
—20622 
1 —  2794 


—  --  26120 
261  18 
26122 

26025 

TAORTT"26045 
26080       26966 

—  26218 
-26  I  f8 

—  26  J  84 
26042 
26277 


-26576 
26575 
26934 


Plate  4,  Figure  236. 

that  the  spring  should  exert  sufficient  force  to  hold  the  idler  in 
constant  contact  with  the  sprocket  and  with  sufficient  force 
to  prevent  the  film  from  climbing  the  teeth. 

No.  16. — The  framing  device,  which  consists  of  parts  26130 
and  26131,  P.  2,  and  parts  26138,  26137,  and  26136,  P.  3,  accom- 


484  MOTION    PICTURE    HANDBOOK 

plishes  the  framing  of  the  picture  by  bending  the  film  inward 
over  the  top  of  the  intermittent  sprocket.  Rollers  26131  (two  of 
them),  may  be  removed  by  loosening  the  small  set  screw  in 
the  base  of  the  casting  and  pulling  outward  on  the  roller. 
Each  roller  is  mounted  on  a  short  spindle  and  is  entirely 
independent  of  its  mate.  Part  26130,  P.  2,  which  carries  these 
rollers,  may  be  removed  by  loosening  the  set  screw  in  its 
hub  and  pulling  outward  on  the  casting.  In  replacing  this 
part,  be  sure  and  get  the  point  of  the  set  screw  entered  into 
the  countersink  in  the  shaft.  Otherwise  the  arm  will  not 
set  right  and  the  framing  of  the  film  will  not  be  properly 
accomplished.  The  removal  of  part  26130,  P.  2,  also  releases 
the  spindle  carrying  it  and  the  roller  on  the  opposite  side 
which  is  connected  with  the  top  of  link  26137,  P.  3,  and  by 
connecting  the  top  end  of  the  link  the  spindle  and  arm  may 
be  pulled  out.  The  framing  lever  itself  can  be  removed  from 
the  cast  lug  to  which  it  is  attached  or  the  lug  and  the  lever 
may  be  detached  by  taking  out  26144,  P.  4. 

No.  17.— Film  gate  26109,  P.  1,  is  operated  by  gate  lever 
26120,  P.  4.  The  raising  of  this  lever  closes  the  gate  and  locks 
it.  Conversely,  the  lowering  of  the  lever  unlocks  the  gate 
and  releases  the  film.  The  gate,  its  top  roller,  lever  and  link 
are  shown,  together  with  the  aperture  plate  in  detail  in  P.  5. 
The  film  gate  and  its  assembled  parts,  as  shown  in  P.  5,  may 
be  released  from  the  mechanism  as  a  whole  by  taking  out 
screw  26121,  P.  3,  the  screw  which  fits  into  hole  X,  P.  5,  and 
loosening  the  small  set  screw  in  the  lugs  holding  the  front 
end  of  the  two  rods  upon  which  the  gate  slides  and  driving 
the  rods  out,  using  a  hard  wood  punch  from  the  back  end. 

No.  18.— The  aperture  plate  26095,  P.  3  and  5,  is  released  by 
taking  off  knurled  knobs  (two  of  them)  26103,  P.  1  and  5. 
The  aperture  plate  tracks  (see  General  Instruction  No.  11) 
consists  of  a  thin  strip  of  highly  tempered  spring  steel  (26100 
right,  26101  left,  P.  5),  held  down  by  two  metal  strips  26098, 
P.  5.  These  strips  may  be  removed  by  the  simple  process  of 
taking  out  the  eight  screws  which  hold  strips  26098,  P.  5,  in 
place,  whereupon  new  strips,  secured  from  the  Edison  Com- 
pany, can  be  put  in  by  being  clamped  under  the  metal  strips. 

Tension  bars  26110,  P.  5  and  1,  are  of  hardened  tool  steel 
and  should  wear  indefinitely.  They  are  held  in  place  by  two 
guide  screws,  one  of  which  is  shown  at  26112,  P.  3,  and  are 
supplied  with  tension  by  two  bow-shaped  flat  springs,  one  at 
<:he  top  and  one  at  the  bottom,  upon  which  the  points  of 
screws  26885  (two  of  them)  bear,  7712,  P.  3,  being  the  lock 


FOR  MANAGERS  AND  OPERATORS 


485 


nut  of  these  screws.  The  tension  on  the  film  (see  General 
Instruction  No.  9)  may  be  used  at  the  will  of  the  operator 
by  adjusting  screws  26885,  P.  3.  Should  it  ever  become 
necessary  to  take  out  either  one  of  the  tension  bars,  26110, 
P.  1,  it  may  be  done  by  removing  screw  26112.  This  will 
release  the  tension  springs  also  and  they  will  drop  out.  The 
roller  at  the  bottom  of  the  aperture  plate  may  be  removed 
by  taking  out  a  small  countersunk  set  screw  in  the  center  of 
the  roller  and  pulling  out  pin  26107,  P.  3.  The  same  thing  is 
also  true  of  the  roller  at  the  top  of  the  gate. 

No.  19. — The  motor  driving  the  machine  is  controlled  by  a 
switch  located  underneath  the  machine,  attached  just  in  front 
of  the  lamphouse  on  the  operating  side.  This  switch  is  a 
special  two-pole,  single-throw  switch  and  is  he-Id  closed  by 
means  of  a  magnet.  This  magnet  is  only  placed  in  operation 
when  the  machine  is  threaded  so  that  the  film  holds  the 
automatic  stop  26131,  P.  3,  in  an  upright  position.  This  stop 
rests  against  the  film,  and  when  in  this  position  the  magnet 
of  the  aforementioned  switch  is  electrified  and  holds  the 
switch  in  running  position,  but  should  the  film  at  any  time 
break,  or  at  the  end  of  the  film,  there  being  nothing  to  sup- 
port automatic  stop  26131,  P.  3,  it  drops  down,  thus  breaking 
the  magnet's  circuit  and  opening  the  motor  switch,  where- 
upon the  machine  in- 
stantly stops.  This  ar- 
rangement is  entirely 
automatic  in  its  opera- 
tion. 

The  automatic  stop 
as  a  whole  may  be  re- 
leased from  the  ma- 
chine by  taking  off  the 
set  screws  in  the  face 
of  part  26253,  P.  2,  and 
pulling  out  spindle 
26252,  P.  1. 

No.  20. — Vertical  drive 
shaft  26066,  P.  2,  may 
be  pulled  out  from  the 
top  after  releasing  set  Plate  5  Figure  237. 

screw     26025     (two     of 
them),   P.  2. 

No.  21. — The  general  construction  of  the  take-up  tension  is 
shown,  assembled  and  in  detail,  in  P.  6.    The  upright  shaft 


486  MOTION    PICTURE   HANDBOOK 

26519,  P.  6,  consists  of  an  outer,  hollow,  and  an  inner,  smaller, 
solid  member,  the  tip  of  which  is  hardened  and  supports  a 
small,  steel  ball  19957.  Part  26503  rests  upon  and  is  supported 
by  this  steel  ball  and  its  top  end  connects  with  upright 
shaft  26066,  P.  2.  This  shaft  is  supported  at  its  lower  end  by 
a  knurled  knob  26513,  P.  6,  and  by  loosening  lock  nut  26022 
and  tightening  up  on  knurled  knob  26513,  the  tension  of  the 
take-up  may  be  increased  or,  by  slacking  off  on  the  knurled 
knob,  the  take-up  tension  may  be  decreased.  The  tension  is 
supplied  by  friction  with  washer  26506,  which  is  clamped  be- 
tween parts  26505  and  26503.  The  diameter  of  the  friction 
disc  is  2  15/16  inches. 

No.  22.— The  intermittent  sprocket  26148,  P.  2,  is  pinned  to 
its  shaft.  It  may  be  removed  therefrom  by  taking  out  screws 
26158,  P.  3  (five  of  them),  which  releases  the  oil  well  cover, 
star,  intermittent  sprocket,  sprocket  shaft  and  collar.  Next, 
with  a  small  punch,  carefully  supporting  the  hub  of  the  sprocket, 
drive  out  the  pins  and  then  loosen  set  screws  in  collar  26153, 
P.  2.  You  may  then  pull  out  the  shaft  and  star,  thus  releasing 
the  sprocket,  and  may  substitute  a  new  one.  I  would  not, 
however,  advise  the  operator  to  do  this.  The  Edison  Com- 
pany assures  me  that  it  can  send  out  the  oil  well  cover, 
intermittent  sprocket,  shaft  star  (one  piece),  assembled,  and 
that  it  will  fit  perfectly.  This  being  the  case,  I  would  very 
strongly  advise  purchasers  of  Edison  Super-Kinetoscopes  to 
have  an  extra  oil  well  cover  with  the  parts  it  carries  as- 
sembled all  ready  to  put  in.  This  would  be  comparatively  in- 
expensive and  would  enable  you  to  send  the  old  part  in  to  the 
factory,  where  the  repair  can  be  made  in  the  best  possible 
manner.  It  is  a  very  delicate  operation  to  install  an  inter- 
mittent sprocket  and  one  which  but  few  operators  are 
equipped  to  do  and  do  right. 

The  Edison  intermittent  movement  is  of  the  familiar  star 
and  cam  type,  both  the  star  and  cam  pins  being  glass  hard- 
ened, the  grinding  being  done  after  hardening.  The  movement 
has,  however,  one  exceedingly  important  peculiarity.  It  is  "ac- 
celerated," or,  in  other  words,  made  faster  than  such  a  move- 
ment would  normally  act  so  that  the  movement  as  assembled 
is  a  trifle  faster  than  6  to  1,  which  gives  you  a  true  50-50 
three-wing  shutter,  The  mechanism  which  accelerates  the 
movement  is  located  behind  the  intermittent  movement  in 
the  oil  well.  I  am  not  going  to  give  directions  for  the  re- 
moval of  this  mechanism  because  I  don't  think  it  practical 


FOR    MANAGERS    AND    OPERATORS 


487 


for  the  operator  to 
undertake  it.  He  might 
get  it  out,  but  it  is 
extremely  doubtful  that 
he  would  be  able  prop- 
erly to  reassemble  the 
parts.  The  accelerating 
movement  rims  in  oil 
and  it  is  extremely 
unlikely  that  it  will  re- 
quire any  attention 
until  the  whole  mech- 
anism is  sufficiently 
worn  to  require  being 
sent  back  to  the  factory 
for  overhauling. 

No.  23. —  Adjusting 
the  intermittent  move- 
ment. (See  General 
Instruction  under  No. 
5.)  The  adjustment  of 
the  star  and  cam  is  ac- 
complished by  loosen- 
ing heavy  round  head- 
ed set  screw  26170,  P.  3,  just  back  of  the  intermittent  move- 
ment oil  well  cup  and  then  shifting  lever  26169,  P.  2.  If  you 

raise  the  lever  26169  up, 
you  tighten  the  move- 
ment and  conversely  by 
lowering  it  you  loosen 
the  movement. 

Caution:  Don't  forget 
to  tighten  up  set  screw 
26170  when  you  get 
through. 

No.  24.— The  inter- 
mittent movement  oil 
well  is  fed  by  oil  cup 
26164,  P.  1.  This  cup 
should  be  kept  level 
full.  (See  General  In- 
Plate  7,  Figure  239.  struction  No.  1.)  At 

the   bottom    of   the   oil 

well   is   a   drain,   and   once   each    week  the   operator   should 
clean  the  oil  well  out  and  fill  it  with  oil.     Once  a  month  it 


Plate  6,  Figure  238. 


488 


MOTION    PICTURE    HANDBOOK 


would  be  a  good  plan  to  drain  out  the  oil  well  and  fill  it  with 
kerosene  and  run  the  machine  say  one-half  a  minute,  after 
which  drain  out  the  kerosene  and  refill  with  oil. 

No.  25. — Lens  ring  adapters.  Lens  carrier  26194,  P.  3,  is 
fitted  with  a  metal  lining  called  an  "adapter."  These  adapters 
are  furnished  in  three  styles,  accomodating  any  standard  lens. 

No.  26. — Revolving  shutter  26247,  P.  1,  may  be  removed 
from  the  mechanism  simply  by  taking  out  thumb  screws  26245 
(four  of  them),  P.  5.  In  assembling  be  sure  to  get  casting 
26243,  P.  1,  right  side  up  so  that  the  shutter  spindle  fits  into 
the  right  ends  of  the  lower  three  gears  as  you  stand  facing 
the  lens  in  the  machine.  It  is  possible  to  turn  the  casting  the 
other  way  to  fit  the  shutter  of  the  other  gear,  but  this  is 
only  designed  for  special  purpose  which  will  be  explained  by 
the  Edison  Company  upon  request. 

For  setting  the  shutter,  see   General  Instruction   No.  18. 

Plate  7  shows  the  construction  of  the  condenser  holder,  and 
the  means  for  spacing  the  lens. 

Parts  on  Plate  No.  1. 


26494     Mechanism   upper  fire  door. 
26025     Upper     sprocket     shaft     oil 

cup     with    tube 
26074     Upper      sprocket      coupling 

with   pin. 

26071     Upper  sprocket. 
26205     M.      P.      lens     'holder      adj. 

screw    knob 
79      M.   P.  obj.    lens  holder   feed 

nut   spring-   screw. 

26114  Film  gate  tension  roller. 

26115  Film     gate     tension     roller 

bracket. 

26117     Film     gate     tension      roller 
bracket   spring. 

26116  Film     gate     tension     roller 

bracket    pin. 
26200      M.     P.      obj.     lens     adapter 

ring  locating  screw. 
26927  Ext.  rev.  shutter  hub. 
26968  Rev.  shutter  main  shaft 

helical  gear  set  screw. 
26068     Rev.     shutter     main     sliaft 

gear. 

26109  Film  gate. 

26110  Film  tension  bars. 

26111  Film  tension  spring. 
26135     Framing     device    adj.     rod. 
26164     Cam  crank  shaft  barrel  oil 

cup  with  holder. 
7044     M.    P.    obj.    lens    feed    nut 

spring  adjusting  screw. 
2782     M.  P.   obj.   lens  holder  feed 

nut  screw. 


1714  M.  P.  obj.  lens  holder  slide 
rod  set  screw. 

26245  Ext.  rev.  shutter  shaft 
bracket  screws. 

26243  Ext.  rev.  shutter  shaft 
bracket. 

26204  M.  P.  obj.  lens  holder  ad- 
justing screw. 

26968  M.  P.  lens  holder  adj. 
screw  collar  set  screw. 

26198  M.   P.   obj.   lens  holder  feed 

nut    spring. 

26199  M.   P.   obj.   lens  holder  feed 

nut  spring  guard. 

26202  M.  P.  obj.  lens  holder  up- 
per slide  rod. 

26270  Ext.  rev.  shutter  inter, 
gear  with  hub. 

26275  Ext.  rev.  shutter  interme- 
diate gear  stud. 

26247     Ext.  rev.   shutter  assem. 

26201     M.      P.      obj.      lens      holder 

lower  slide  rod. 

13     Ext.      rev.      shutter     flange 
screws. 

26928  Ext.  rev.  shutter  clamping 
flange. 

26239     Ext.   rev.   shutter  shaft. 

26926  Ext.  rev.  shutter  blade 
holder. 

26245  Ext.  rev.  shutter  shaft 
bracket  screws. 


FOR    MANAGERS    AND    OPERATORS 


489 


Parts  on  Plate  No.  2. 


26459 
26191 

26025 
26066 
20622 

26580 
18419 
26277 

26169" 
18432 

43 

26025 
26130 
26178 
26576 
26577 
26188 

26934 
26191 

26025 


7084 
26564 
26566 

26578 
26-089 

26969 

2798 

26022 


Vertical  drive  shaft  knob. 
Vertical    drive    shaft    mitre 

gear. 
Vertical  drive  shaft  oil  cup 

with    tube. 
Mechanism     vertical      drive 

shaft. 
Stereo,     lens    holder    hinge 

screw    nut. 
Stereo,  lens  holder. 
Stereo,  lens  adapter  ring. 
Large  inter,   gear  with  first 

inter,   pinion   and   pin. 
Cam  shaft  barrel  lever. 
Stereo,     lens     adapter    ring 

stop    scre'ws. 
Cam      shaft      barrel      lever 

screw. 
Cam    crank    shaft     oil     cup 

with   tube. 
Inter.        sprocket        tension 

roller  bracket. 
Cam      crank      shaft       gear. 

assembled. 
Stereo,     lens     holder     hinge 

screw. 
Stereo,    lens  holder    support 

and   rod   assem. 
Take-up        sprocket       shaft 

mitre     gear     with     pinion 

and    pin. 
Stereo,  lens  slide  rod  clamp 

screw. 

Vertical    drive    shaft    mitre 
.     gear. 
Vertical  drive  shaft  oil   cup 

with    tube. 
Stereo,  lens  bracket. 
Stereo,     lens 

screw. 
Stereo,     lens 

screw  nut. 
Stereo,    lens 

bolt. 
Stereo,     lens    bracket    slide 

rod. 

Stereo,   lens  holder  support. 
Upper  tension  roller  bracket 

spring. 
Upper  tension  roller  bracket 

set   screw. 
Upper  tension  roller  bracket 

spring   screw. 
Mechanism   head. 


bracket     stop 

bracket     stop 

bracket    hinge 


26289      Upper  tension  roller  bracket 

stud  with  head. 
26085     Upper     tension     roller    stud 

(long). 
2347     Upper     tension     roller     stud 

set   screw. 
26085     Film      gate     tension     roller 

stud    (long). 
26073     Rev.     shutter     main     shaft 

end   plate   screws. 
26061     Rev.      shutter     main     shaft 

end    plate    with    bushing 

and    pins. 

26131     Framing    device    roller. 
26105     Aperture   plate   lower  roller 

body. 
26969     Framing         device         roller 

bracket    screw. 
Aperture  plate  roller  ends. 
Framing         device         roller 

bracket. 
Inter.          sprocket          roller 

bracket    set    screw. 
Inter.        sprocket       bracket 

with    bushing. 
26148     Inter,    sprocket. 
26153      Star   wheel   shaft   collar. 
26152      Star    wheel    with    shaft. 
26085     Inter.         sprocket        tension 

roller    stud    (long). 
26155     Inter.        sprocket       bracket 

adapter   plate. 
2347     Tension      roller      stud      set 

screw. 

26035      Driving    crank   coupling. 
26037     Driving   crank   stop  screw. 

26085  Take-up  tension  roller  stud 

(long). 
26091      Take-up         tension        roller 

bracket. 
26025      Take-up    sprocket   shaft    oil 

cup    with    tube. 

26086  Take-up         tension         roller 

bracket   stud  with  head. 
26085     Motor       stop       roller      stud 

(long). 
26969     Take-up         tension        roller 

bracket   set   screw. 
26260      Motor    stop    roller    bracket 

spring. 
2798     Take-up        tension        roller 

bracket    spring   screw. 
260S9     Take-up         tension        roller 

bracket    spring. 


Parts  on  Plate  No.  3. 


260S2  Upper  tension  roller  bracket. 
26078  Upper  sprocket  clutch  screw. 
26083  Upper  tension  roller. 
26121  Film'gate  shift  rod  bracklet. 
26207  Auto,  drop  shutter  with 
counterbalance. 


26095     Aperture    plate    and    studs, 

assem. 

26098     Film    guide. 
26191     Mitre    gear. 
26885     Film    tension    spring   screw. 
26499     Auto,    drop   shutter   screws. 


490 


MOTION    PICTURE    HANDBOOK 


26112     Film  tension  bar  screw. 

26100  Film  spacer  (right). 

26101  Film  spacer  (left). 

7712     Film    tension    spring    screw 

lock  nut. 

20622     Large  inter,  gear  stud  nut. 
26138     Framing    device    link    stud 

knurled    nut. 
26137     Framing     device     adj.     rod 

link. 
26158     Inter.       sprocket       bracket 

screws  (long). 
26136     Framing     device    adj.     rod 

bracket. 
26083     Inter.        sprocket       tension 

roller. 

26083     Take-up   tension  roller. 
26074     Take-up    sprocket    coupling 

with    pin. 

26071     Take-up  sprocket. 
26078     Take-up      sprocket      clutch 

screw. 

26131     Motor   stop    roller. 
26253     Motor  stop   roller  bracket. 
15642     Motor  stop  arm  stop  screw. 
26809     Motor  stop   arm   with  tip. 
2794     Mechanism  case  left  corner 

plate    screws. 
26875     Motor     stop     push     button 

socket. 

26872     Motor    stop   push    button. 
7712     Motor  stop  arm  stop  screw 

lock   nut. 

26945     Magazine  film  guide  rollers. 
26292     Magazine   film   guide   roller 

shaft. 
26291     Lower  film  guide  roller. 


26292     Lower     film     guide     roller 

shaft. 
26498     Mechanism   upper  flre  door 

hinge    screw. 

26126  Film    gate     shift    rod    link 

screw    (large). 

26127  Film     gate     shift    rod     link 

screw    (small). 

26105  Aperture  plate  upper  roller 

body. 

26106  Aperture  plate   upper  roller 

ends. 

26107  Aperture  plate  upper  roller 

shaft. 
26153     M.      P.      lens     holder     adj. 

screw    collar. 

15703     Film  guide   screws. 
1714     M.   P.   obj.  lens  holder  slide 

rod   set  screw. 
26103     Aperture      plate      clamping 

nuts. 

26194  M.   P.   obj.    lens  holder. 
26067     Rev.     shutter     main     shaft 

mitre  gear. 

26195  M.     P.     obj.     lens     adapter 

ring. 
26049     Rev.     shutter     main     shaft 

mitre    gear   screw. 
26069     R'ev.    shutter  main   shaft. 

26196  M.     P.     obj.     lens    adapter 

ring   clamp   screw. 
26103     Aperture      plate      clamping 

nuts. 
26107     Aperture   plate  lower  roller 

shaft. 

26170     Cam  shaft  barrel  set  screw. 
26028     Cam  crank  shaft  oil  cup. 
26690     Driving   crank   assem. 


Parts  on  Plate  No.  4. 


89  Ext.  rev.  shutter  blade 
screws. 

26068  Ext.  rev.  shutter  counter- 
shaft gear. 

26224  Ext.  rev.  shutter  counter- 
shaft. 

26277  Large  inter,  gear  with  first 
inter,  pinion  and  pin. 

26042     Large  inter,   gear  stud. 

26031     Mechanism    driving    gear. 

26033  Mechanism  driving  gear 
screw. 

26290     Mechanism  base. 

26574  Stereo,  lens  holder  slide  rod. 
26153     Stereo,     lens     bracket     adj. 

screw  collar. 

26575  Stereo,    lens  holder  support 

rod    bracket. 

26934  Stereo,  lens  holder  support 
rod  clamp  screws. 

26576  Stereo,     lens    holder    hinge 

screw. 


Stereo,     lens    slide    bracket 

rod  set  screw. 
Stereo,    lens    slide    bracket 

hinge  bolt  nut. 
M.   P.  ob.i.   lens  holder  feed 

nut. 
Vertical  drive  shaft  oil  cup 

with   tube. 
Film  gate  shift  rod. 
Film  gate  slide  rod. 
Film    gate    shift    rod    link, 


2794 
20622 
26197 
26025 

26120 
26118 
26122 


26025  Ext.  rev.  shutter  counter- 
shaft oil  cup  with  tube. 

26045     Second  inter,  pinion,  assem. 

26080  Rev.  shutter  main  shaft 
collar. 

26966  Rev.  shutter  main  shaft 
collar  set  screw. 

26043  Second  inter,  pinion  sliaft 
assembled. 

26218  Auto,  drop  shutter  clutch 
cover. 


FOR    MANAGERS  AND    OPERATORS  491 

26118     Film   grate   slide    rod.  26567  Stereo,    lens  bracket   base. 

26184     Cam    crank   shaft   pulley. 

26186     Cam     crank     shaft     pulley  -6570  stereo-     lens     bracket     adj. 

screw.  screw   knob 

26025     Vertical     driver     shaft     oil  26569  Stereo,     lens    bracket     adj. 

tube.  screw. 

26019     Mechanism  head  bolts.  L'6563  Stereo,  lens  bracket  slide. 

Parts  on  Plate  No.  5. 

26114  Film    gate    tension   roller.  26117  Film     gate     tension     roller 

26115  Film     gate     tension     roller  bracket    spring. 

bracket.  26120  Film  gate  shift  rod. 

26116  Flte10n     r°ller  26122  Filra    *ate    shift    rod    link- 


26117     Film     gate     tension     roller  assem. 

bracket    spring.  26126  Film    gate    shift    rod     link 

26109  Film    gate.        .  screw     (large). 
26111     Film    tension   spring.  26110  Film   tension  bars. 

Film   tension  bar  screw.  26103  Aperture      plate      clamping 

26110  Film   tension   bars.  ^uts 

26885     Film   tension   spring   screw.  2fi09fi  Anprt  '       nlfltp 

26121  Film  gate  shift  rod  bracket. 

26126     Film    gate    shift    rod    link  26098  Fllm  SuiAe. 

screw    (large).  26100  Film  spaced    (right). 

26122  Film    gate    shift    rod    link,  15703  Film    guide     screws     (8     of 

them). 


Power's  Six-B  Mechanism 

THE  Power's  No.  6  Mechanism  is  of  the  "open"  type  in 
that  it  has  no  protecting  casing.  Thus  all  the  gears 
and  machinery  are  directly  under  the  eye  of  the 
operator.  In  referring  to  these  instructions  the  numbers 
refer  to  parts  and  plates.  Thus:  738,  P.  2,  means  that  the  part 
indicated  is  shown  in  Plate  2,  which  in  this  case  is  the  screw 
holding  the  upper  and  the  lower  sprockets  to  the  shaft. 

No.  1.  Removing  Main  Driving  Gear  and  Spindle. — To 
remove  main  driving  gear  630,  P.  4,  and  its  spindle  631,  P.  4 
and  7,  first  remove  crank  632,  P.  5,  and  taper  pin,  795,  P.  2, 
which  engages  the  slot  in  the  hub  of  the  crank.  This  is  a  taper 
pin  and  in  the  later  machines  a  prick  punch  mark  will  be 
found  on  the  end  of  shaft  631  P.  4.  This  mark  is  opposite 
the  large  end  of  the  pin.  Having  removed  this  pin,  the  'shaft 
and  gear  may  be  withdrawn,  and,  if  desired,  the  gear  may 
be  removed  from  the  shaft  by  taking  out  the  taper  pin  in 
its  hub. 

No.  2.  To  Remove  Shaft  618,  P.  4,  Carrying  Gears  620  and 
619,  P.  4,  first  follow  Instruction  No.  1,  then  loosen  screw 
738,  P.  2,  backing  it  off  some  distance,  as  it  is  countersunk 
into  the  shaft,  whereupon  the  shaft  and  gear  may  be  with- 
drawn from  the  gear  side. 


492 


MOTION    PICTURE   HANDBOOK 


No.  3.  Removing  Automatic  Fire  Shutter  Governor  Cover. 
— To  remove  automatic  fire  shutter  governor  cover  623,  P.  2, 
loosen  screw  718,  P.  2,.  backing  it  off  somewhat,  as  it  is 


Figure  240. 

countersunk  into  the  shaft.  This  releases  cover  623  (also 
shown  at  the  left  in  Plate  8).  If  the  cover  does  not  readily 
pull  off,  tap  gently  on  the  end  of  the  shaft,  at  the  same  time 
pulling  on  the  cover. 

Caution:  Don't  try  to  pry  the  cover  off  by  inserting  a 
screwdriver  point  between  part  623  and  624,  P.  2.  If  you  do 
you  will  probably  merely  succeed  in  ruining  your  governor. 

No.  4.  To  Remove  Friction  Casing  of  Automatic  Fire 
Shutter,  624,  P.  2. — Follow  Instruction  No.  3,  then  remove 
screw  785,  P.  7,  whereupon  part  624  may  be  pulled  away. 

No.  5.  To  Remove  Automatic  Fire  Shutter  Link  628  and 
Lever  627,  P.  7,  follow  Instruction  Nos.  3  and  ^,  after  which 
the  parts  are  released  by  taking  out  a  screw  on  the  back  side 
of  part  624. 

No.  6.  Adjusting  Fire  Shutter  Governor. — Should  auto- 
matic fire  shutter  blade  697,  P.  1,  fail  to  drop,  examine  lever 
627,  and  link  628,  P.  7,  and  see  that  they  work  freely  and  are 


FOR  MANAGERS  AND  OPERATORS 


493 


not  bent.  Usually  the  binding  of  these  parts  is  responsible 
for  the  sticking  of  the  fire  shutter.  If  this  is  not  found  to 
be  the  seat  of  the  trouble,  remove  cover  623,  P.  2  (see  In- 
struction No.  3),  and  carefully  examine  springs  741,  P.  8; 
also  examine  the  inside  edge  of  friction  casing  624,  P.  2,  and 
see  if  track  "Y,"  Fig.  8,  is  smooth,  as  it  should  be,  and  not 


Plate  1,  Figure  241. 

scratched  or  rough.  If  it  is  rough  or  scratched,  carefully 
polish  track  "Y"  by  using  No.  00  emery  cloth. 

Caution.  Do  not  use  coarse  emery  cloth,  or  you  will  only 
succeed  in  making  matters  worse. 

Should    the   automatic    fire   shutter   fail    to    raise    properly, 


494  MOTION    PICTURE   HANDBOOK 

first  try  injecting  a  drop  of  heavy  oil  in  the  oil  hole  on  top  of 
part  624,  P.  2.  The  clutch  shoes,  625,  P.  8,  act  by  centrifugal 
force,  which  throws  out  weights  626,  P.  8,  against  the  action 
of  springs  741,  P.  8,  thus  forcing  friction  shoes  625  against 
track  "Y,"  P.  8.  The  friction  thus  engendered  revolves  cas- 
ing 624  in  clockwise  direction,  thus  forcing  lever  627,  P.  7, 
ahead  and  raising  shutter  flap  697,  P.  1.  Don't  use  thin  oil 
on  the  automatic  shutter  governor,  as  it  tends  to  reduce  the 
friction  too  much.  Use  heavy  oil  and  use  it  sparingly. 
Should  the  fire  shutter  raise  too  quickly,  or  should  the  gov- 
ernor develop  undue  friction,  thus  making  the  mechanism 
pull  hard,  it  will  probably  be  found  that  springs  741,  P.  8, 
have  become  weakened.  This  may  be  remedied  by  installing 
new  springs,  or  stretching  the  old  ones.  Another  possible 
cause  of  failure  of  the  fire  shutter  to  act,  or  to  act  too  slowly, 
is  the  binding  of  the  screws  at  the  top  or  lower  end  of  link 
628,  P.  7.  This  link  must  swing  perfectly  free.  In  the  center 
and  top  of  fire  shutter  flap  697,  P.  1,  is  a  pin.  This  pin  not 
only  serves  to  hold  the  flap  to  its  spindle,  and  prevent  its 
slipping  circumferentially,  but  it  also  prevents  the  shutter 
from  raising  too  high.  Therefore,  it  should  not  be  allowed 
to  become  loose  'and  fall  out  Automatic  shutter  governor 
counterweight  629,  P.  2,  should  be  kept  set  in  such  manner 
that  it  stands  about  half-way  between  the  horizontal  and 
perpendicular,  when  the  shutter  flap  is  down,  leaning  out- 
ward toward  the  lamphouse. 

No.  7.  Removing  Top  Roller  Bracket.— Top  roller  bracket 
612,  P.  2  and  7,  may  be  removed  by  taking  out  stud  720,  P.  7. 

No.  8.  Removing  Top  Sprocket  Idler.— Top  sprocket  idler 
609,  P.  2,  may  be  removed  by  loosening  screw  721,  P.  2,  pull- 
ing the  shaft  out  and  taking  off  the  collar  next  the  roller. 
These  rollers  should  be  renewed  if  there  is  any  indication 
of  flat  spots  on  their  surface. 

No.  9.  Removing  Top  and  Bottom  Sprockets.— Top 
sprocket  617,  P.  7,  and  lower  sprocket  646,  P.  2,  may  be  re- 
moved simply  by  loosening  the  set  screw  in  the  center  of 
their  hub,  pulling  the  sprocket  off  the  shaft.  (See  General 
Instructions  Nos.  3  and  4.) 

In  the  later  machines  there  is  a  metal  guard  which  comes 
up  between  the  flanges  of  the  upper  sprocket.  In  order  to 
remove  this  sprocket  it  will  be  necessary  first  to  take  off  this 
guard,  which  may  be  accomplished  by  the  removal  of  two 
screws,  one  in  either  of  its  lower  corners. 

No.  10.  Tension  of  Upper  Idler  Bracket. — Upper  sprocket 
idler  609,  P.  2,  is  held  to  the  sprocket  by  flat  spring  615,  P.  2. 


FOR    MANAGERS    AND    OPERATORS  495 

Should  this  spring  at  any  time  become  too  weak,  it  may  be 
strengthened  by  removing  the  idler  bracket  (see  Instruction 
No.  7)  and  bending  the  top  of  the  spring  outward  until  the 
desired  tension  is  obtained. 

No.  11.  Removing  the  Gate. — The  entire  gate,  including 
cooling  plate  696,  P.  1,  automatic  fire  shutter  flap  697,  P.  1, 
and  hinge  690,  P.  1,  may  be  removed  by  taking  out  screws 
(three  of  them)  782,  P.  1.  In  replacing  the  gate,  before 
tightening  up  screws  782,  P.  1,  be  sure  that  the  top  gate  idler 
rollers  691,  P.  3,  center  properly  with  the  aperture  plate. 
After  replacing  the  gate,  project  white  light  to  the  screen. 
If  there  is  a  shadow  at  the  top,  bottom  or  side,  open  the 
gate.  If  the  opening  of  the  gate  removes  the  shadow,  then 
it  means  that  you  haven't  your  gate  properly  centered,  and 
you  must  loosen  hinge  screws  782,  P.  1,  and  move  the  gate 
until  the  shadow  disappears,  being  careful,  however,  that 
the  upper  idlers  691,  P.  3,  are  kept  spaced  equidistant  from 
the  sides  of  the  aperture  plate. 

No.  12.  Removing  and  Adjusting  Tension  Shoes. — Tension 
shoes  790,  P.  2,  may  be  removed  by  first  pulling  out  the  pin 
in  gate  hinge  690,  P.  1,  after  which  remove  screws  789  (one 
on  either  side),  P.  2.  This  releases  the  tension  shoes. 

No.  13.  Removing  Tension  Springs. — Between  the  face 
of  the  gate  and  cooling  plate  696,  P.  1,  are  the  tension  springs 
and  the  tension  spring  equalizer.  Should  it  at  any  time  be 
necessary  to  remove  either  of  these,  take  out  two  flat  head 
screws  just  above  and  below  the  cross  bar  joining  tension 
shoe  tracks  790,  P.  .2.  This  will  release  cooling  plate  696, 
P.  1,  and  expose,  the  parts.  In  replacing,  be  sure  that  the 
little  flat  spring  which  acts  on  gate  latch  693,  P.  1,  rests 
against  the  latch,  and  not  on  top  of  it. 

No.  14.  Removing  Cooling  Plate. — (See  Instruction  No. 
13.) 

No.  15.  Adjusting  Tension. — (See  General  Instruction  No. 
9.)  The  tension  is  governed  by  screw  734,  P.  1.  Setting  this 
screw  inward  increases  the  tension,  and  conversely,  backing 
off  on  the  screw  decreases  it. 

No.  16.  Aperture  Plate.— Aperture  plate  687,  P.  2,  may 
be  taken  off  by  removing  screws  713  (four  of  them),  P.  2, 
and  pulling  the  plate  away.  In  replacing  the  aperture  plate, 
proceed  as  follows:  Put  the  plate  in  place  and  insert  the 
four  screws  holding  it,  tightening  them  down  just  enough 
so  that  by  tapping  lightly  on  the  edge  of  the  plate  it  may 
be  moved  either  way.  Now  project  the  white  light  to  the 
screen  and  move  the  aperture  until  the  upper  and  lower 


496 


MOTION    PICTURE   HANDBOOK 


lines  of  the  light  are  level  on  the  screen,  whereupon  tighten 
up  the  four  screws  tight. 

Caution. — In  removing  parts  of  this  kind,   remember  that 
the    screws    are    small.      Don't    drop    them    or    lay    them 


Plate  2,  Figure  242. 


down  anywhere,  depending  upon  luck  to  find  them  again. 
Have  a  cigar  box  or  some  small  receptacle  in  which  to  place 
all  screws,  or  in  lieu  of  that  replace  the  screws  in  the  holes 
when  you  take  the  part  away.  Then  you  will  know  where 
they  are  when  you  want  them.  A  magnetized  screwdriver 


FOR    MANAGERS    AND    OPERATORS  497 

is  a  fine  thing  with  which  to  handle  small  screws.  (See 
General  Instruction  No.  19.) 

No.  17.  Adjusting  Gate  Latch  Screw.— The  right-hand 
edge  of  the  face  of  the  gate  and  its  left-hand  edge  should 
set  an  equal  distance  away  from  the  face  of  the  machine 
casting,  since  otherwise  the  tension  on  one  shoe  will  exert 
greater  pressure  than  it  will  on  the  other.  This  is  regulated 
by  gate  latch  screw  722,  P.  2.  This  screw  should  be  set  in  a 
sufficient  distance  to  bring  the  entire  gate  square  with  the 
face  of  the  mechanism  casting,  and  the  lock  nut  thereon 
should  then  be  set  up  tight  to  prevent  any  possibility  of 
change  in  this  adjustment. 

No.  18.  Removing  Intermittent  Roller  Bracket.— Roller 
bracket  659,  P.  2,  may  be  removed  by  taking  out  the  screw 
in  its  hinge,  first,  however,  having  loosened  screws  788,  P.  2, 
holding  spring  663,  P.  2.  The  distance  of  the  idler  which 
this  bracket  carries  from  the  intermittent  sprocket  (see 
General  Instruction  No.  12)  may  be  varied  by  tightening  or 
loosening  screw  719,  P.  2.  To  accomplish  this,  first  loosen 
the  nut  on  its  outer  end,  then  turn  the  bracket  clear  up,  and 
the  head  of  the  screw  will  be  found  underneath.  The  fur- 
ther this  screw  is  backed  out,  the  further  the  roller  will  be 
from  the  sprocket,  and  vice  versa.  The  tension  of  this 
bracket  is  governed  by  flat  spring  663,  P.  2.  This  may  be 
made  greater  or  less  by  bending  the  spring.  If  it  is  to  be 
made  greater,  remove  the  spring  for  bending.  If  it  is  to  be 
made  less,  just  bend  the  upper  end  of  the  spring  outward, 
but  be  careful  not  to  bend  it  too  much. 

No.  19.  Removing  and  Adjusting  Apron. — Apron  669,  P. 
1,  may  be  taken  off  by  removing  two  screws  (one  at  either 
side)  near  the  rollers  at  its  lower  end.  The  adjustment  of  this 
apron  is  quite  important.  Should  the  film  make  a  chattering 
sound  in  going  through  the  machine,  carefully  bend  the  ears 
at  the  lower  end  of  apron  669,  P.'l,  which  carry  the  rollers, 
ahead  slightly,  being  careful  to  bend  each  one  the  same 
amount.  If  this  remedies  the  trouble,  well  and  good.  If  it 
helps  but  does  not  remedy  it  then  try  bending  them  a  little 
more.  If  this  makes  it  worse  bend  the  rollers  back  slightly. 
You  can  do  no  damage  by  bending  these  apron  ears,  pro- 
vided you  keep  the  rollers  square  with  the  sprocket,  that 
is  to  say  equidistant  from  the  sprocket.  To  test  this,  meas- 
ure from  the  face  of  each  hub  of  the  roller!  to  opposite 
teeth  on  the  lower  sprocket. 

No.  20.  Removing  and  Adjusting  Lower  Sprocket  Idler 
Bracket. — Lower  sprocket  idler  bracket  653,  P.  1,  may  be  re- 


498 


MOTION    PICTURE   HANDBOOK 


moved  merely  by  taking  out  its  hinge  screw,  first,  however,  loosen- 
ing screws  711,  P.  2,  holding  flat  spring  658.  The  distance  of 
the  roller  which  this  bracket  carries  from  the  sprocket  (see 
General  Instruction  No.  12)  is  determined  by  the  position 
of  screw  724,  P.  2.  Spring  658,  P.  2,  should  supply  sufficient 
tension  to  this  bracket  to  hold  it  firmly  in  place  when  it  is 


602 


6OI 


Plate  3,  Figure  243. 

closed  down,  but  this  may  be  overdone.  The  tension  should 
not  be  sufficient  to  cause,  the  sprocket  teeth  to  punch 
through,  or  even  seriously  indent  the  film  when  it  climbs  the 
sprocket.  This  adjustment  calls  for  a  little  judgment  and 
common  sense.  If  it  is  too  loose  the  loop  setter  will  work 
overtime.  If  it  is  too  tight  damage  may  and  probably  will 
be  done  to  the  film. 

No.  21.     To  Remove  Fly  Wheel  672,  P.  3,  remove  screw 


FOR    MANAGERS    AND    OPERATORS  499 

709,  P.  3.  If  you  cannot  start  this  screw  with  an  ordinary 
screwdriver,  grind  down  the  broad  end  of  a  file  to  make  a  screw- 
driver for  the  purpose.  Having  removed  this  screw,  place 
the  point  of  the  screwdriver  right  up  close  against  the  hub 
on  the  opposite  side  of  the  wheel,  and  tap  gently  until  the 
wheel  becomes  loose.  In  replacing  the  fly  wheel  be  sure 
that  groove  746  in  pinion  677,  P.  7,  connects  properly  with 
the  dowels  on  the  spindle.  In  order  to  accomplish  this  in- 
sert the  point  of  the  screwdriver  between  lugs  carrying 
brackets  659,  P.  2,  and  the  collar  on  shaft  676,  P.  2,  and  pry 
gently  downward.  This  will  hold  the  spindle  stationary 
while  you  twist  the' wheel  until  tjie  slots  and  dowels  come 
opposite  each  other. 

Caution:  Between  pinion  677,  P.  7,  and  the  hub  of  the  cast- 
ing it  fits  up  against  is  a  thin  steel  washer.  This  washer  fits  on 
the  larger  diameter  of  the  shaft,  and  you  must  be  careful  that 
it  is  precisely  in  place  before  the  wheel  is  forced  on,  or 
you  will  have  trouble.  When  the  wheel  is  in  place,  tighten  up 
screw  709,  P.  3,  tight. 

No.  22.  Removing  Toggle  Gear. — To  remove  toggle  gear 
678,  P.  1  and  7,  follow  Instruction  No.  21,  then  loosen  the 
screw  in  the  upper  end  of  connecting  link  682,  P.  7,  backing  it 
out  for  a  considerable  distance,  since  it  is  countersunk  into  the 
shaft,  whereupon  the  gear  and  spindle  may  be  pulled  out. 
The  adjustment  of  this  gear  is  a  very  important  matter. 
The  gear  must  be  exactly  centered  between  fly  wheel  pinion  677, 
P.  1,  and  gear  680,  P.  3.  The  toggle  gear  is  carried  by 
connecting  link  682,  P.  7,  and  its  position  with  relation  to 
the  gears  on  either  side  of  it  is  determined  by  the  position 
of  the  casting  carrying  the  horizontal  bar.  Should  a  grind 
develop  in  this  gear,  first  having  made  sure  that  connecting 
link  682,  P.  7,  is  held  snugly  in  its  ways  by  casting  685,  P.  7, 
using  a  soft  metal  punch,  tap  lightly  first  one  way  and  then 
the  other  against  casting  684,  P.  7,  the  idea  being  to  slip 
the  casting  slightly  against  the  pressure  of  the  screws  which 
hold  it.  The  casting  cannot  be  moved  much,  but  sometimes 
enough  movement  may  be  accomplished  to  remove  or  re- 
duce a  grind. 

No.  23.  Adjusting  Connecting  Link. — Connecting  link 
682,  P.  7,  plays  an  important  part,  and  must  be  kept  tight 
in  its  ways.  If  by  shaking  horizontal  bar  683,  P.  7,  you  are 
able  to  move  connecting  link  682  in  its  ways,  then  it  is  too 
loose,  and  may  be  tightened  as  follows:  First  loosen 
screws  745,  P.  7,  slightly.  Then  tighten  up  just  a  little  on 
screws  744  (two  of  them),  P.  7,  retighten  screws  745  and 


500 


MOTION    PICTURE    HANDBOOK 


try  the  framing  lever.  If  it  works  too  hard,  you  have  moved 
screws  744  too  much.  If  it  is  still  too  loose,  then  you  can 
give  them  a  little  bit  more,  but  be  careful  and  do  not  get 
them  too  tight  or  your  framing  carriage  will  bind.  In  mak- 
ing this  adjustment,  do  not  set  screws  744  in  so  much  that  the 


727 


777 


Plate  4,  Figure  244. 

connecting  link  fits  snugly  while  screws  745  are  loose,  for  if  you 
do  when  you  tighen  screws  745,  the  whole  thing  will  be  clamped 
solid.  When  you  get  through  with  this  job,  be  sure  that  screws 
745  and  the  lock-nuts  on  screws  744  are  set  up  tight. 

No.  24.  Removing  Lower  Sprocket  Shaft. — To  remove 
lower  sprocket  shaft  loosen  screw  738,  P.  1,  and  pull  the 
shaft  out  to  the  left.. 

No.   25.     Removing   Large    Idler   Gear. — To    remove    large 


FOR    MANAGERS    AND    OPERATORS  501 

idler  gear  640,  P.  4,  remove  the  mechanism  from  the  machine 
table,  turn  it  bottom  side  up  and  looking  in  you  will  see  the 
shaft  which  holds  this  gear,  and  on  it,  right  up  against  the 
machine  casting,  a  brass  collar,  the  stock  number  of  which 
is  642.  Revolve  the  fly  wheel  until  the  set  screw  in  this 
collar  comes  into  view.  Loosen  the  set  screw  and  you  may 
then  pull  the  gear  and  its  shaft  out. 

No.  26.  Removing  the  Loop  Setter. — Loop  setter  fork 
768,  P.  4,  may  be  removed  by  first  following  Instructions 
Nos.  24  and  25.  Then  remove  screw  767,  P.  4,  which  will 
release  the  fork  and  clutch  766,  P.  4.  Loop  setter  cam  761, 
P.  4,  is  removed  by  following  Instructions  24  and  25,  loosen- 
ing the  two  large  screws  in  its  face  and  pulling  it  off  the 
shaft.  Should  it  be  necessary  to  remove  the  loop  setter  arm, 
carrying  roller  769,  P.  3,  or  the  spring  which  provides  ten- 
sion therefor,  first  follow  Instructions  24  and  25;  then  loosen 
screws  780  (three  of  them),  P.  4.  Having  removed  these 
screws,  the  entire  arm,  including  roller  769,  P.  3,  may  be 
pulled  out  through  the  hole  in  the  machine  casting.  The 
replacement  of  these  parts  is  merely  a  reversal  of  the 
process  of  their  removal,  but  in  replacing  them,  be  sure 
that  all  screws,  particularly  screws  780  and  the  screws  in 
cam  761,  be  set  up  tight.  In  replacing  the  loop  setter,  be 
careful  that  roller  769,  P.  3,  lines  properly  with,  the  lower 
sprocket,  or,  in  other  words,  that  the  roller  sets  perfectly 
"square  with  the  film,"  since  otherwise  when  the  loop 
setter  acts  the  pull  will  be  all  on  one  side  of  the  film,  which 
may  and  probably  will  cause  trouble. 

No.  27.  Adjusting  the  Loop  Setter.— Screw  782,  P.  4,  is 
for  the  purpose  of  adjusting  or  regulating  the  throw  of 
loop  setter  arm  and  roller  769,  P.  3.  This  screw  should  be  so 
adjusted  that  roller  769,  P.  3,  rests  about  half-way  between 
the  lower  sprocket  and  the  top  of  the  front  cross  bar  in  the 
base  of  the  machine. 

No.  28.  The  Shutter  Bracket. — When  a  new  machine  is 
received,  shutter  bracket  637,  P.  4,  will  be  folded  down 
against  the  mechanism  and  shutter  blade  700,  P.  6,  will  be 
tied  to  the  mechanism.  Raise  up  shutter  bracket  637,  P.  4,  until  it 
is  in  a  horizontal  position,  as  shown  in  plate  4,  and  screw  732,  P. 
4,  has  engaged  the  hook  on  the  upper  part  of  the  bracket,  first 
having  backed  screw  732  out  sufficiently  so  that  the  hook 
will  pass  in  behind  its  head.  Now,  having  raised  the  bracket 
clear  up,  tighten  screw  732,  P.  5,  tight,  and  then  'tighten  screw 
733  tight. 

Caution:     Do  not  tighten  screw  733  until  you  have  tight- 


502 


MOTION    PICTURE    HANDBOOK 


ened  screw  732,  because  if  you  do  it  will  probably  cause  the 
shutter  spindle  to  bind  in  the  bracket.  The  entire  shutter 
bracket,  637,  P.  4,  may  be  removed  from  the  machine  by 
first  following  Instructions  Nos.  1,  24  and  25,  and  loosening 

737 


754 


Plate  5,  Figure  245. 

screw  732,  P.  4,  and  733,  P.  5.  Then  drive  out  the  taper  pin 
in  the  hub  of  gear  680,  P.  3,  and  drive  out  shaft  681,  P.  3, 
carrying  with  it,  on  the  opposite  end,  gear  633  and  634,  P.  4. 
To  drive  this  spindle  out,  use  a  heavy  nail  or  a  center  punch. 


FOR    MANAGERS   AND    OPERATORS  503 

No.  29.  Removing  Shaft  681,  P.  3,  and  Gears  633  and  634, 
P.  3.— See  Instruction  No.  28. 

No.  30.  Installing  Shutter  Driving  Gears  633,  634,  and  635, 
P.  4. — Do  not  attempt  it.  If  these  gears  need  replacing,  it  will 
be  necessary  to  send  the  machine  to  the  factory,  or  to  a 
thoroughly  competent  repair  man.  The  same  applies  to  the 
shutter  shaft  636,  P.  4.  It  would  be  hardly  possible  for  the 
operator  to  replace  either  gears  633,  634,  or  635,  or  to  put  in  a 
new  revolving  shutter  shaft,  and  get  the  parts  so  adjusted  that 
they  would  run  right. 

No.  31. — In  P.  6  we  see  a  three-blade  shutter.  This  blade 
may  be  changed  to  a  two-blade,  using  the  same  hub,  by 
loosening  screw  740,  P.  6,  pulling  the  shutter  off  its  shaft 
and  removing  three  screws  in  the  back  of  its  hub.  This 
releases  the  shutter  blade,  which  may  then,  if  desired,  be 
changed  to  another  one  of  different  design. 

No.  32.  Setting  the  Shutter.— (See  General  Instruction  No. 
18.)  Shutter  700,  P.  6,  may  be  set  by  loosening  screws  739,  P. 
6,  in  its  hub,  which  will  allow  the  outer  hub  to  revolve  on 
the  inner,  thus  enabling  the  operator  to  set  the  shutter  in  any 
desired  position. 

No.  33.  Removing  Oil  Casing  Cover. — To  remove  oil 
casing  cover  674,  P.  4,  follow  Instructions  Nos.  24  and  25. 
Next  remove  screws  794  (three  of  them),  P.  4,  and  tap 
lightly  on  the  hub  of  the  cover  to  break  the  shellac  joint. 

In  replacing  this  cover  scrape  the  edges  lightly,  being 
sure  to  get  them  perfectly  clean.  Then  smear  edge  of  the 
cover  (not  casing  edge,  but  the  cover  edge  only}  with  thick 
shellac,  to  be  had  of  any  painter,  and  clamp  the  cover  in 
place.  It  is  better  if  the  shellac  dries  a  little  before  you  put 
the  cover  on,  but  don't  let  it  dry  too  much. 

Caution:  Don't  put  on  too  much  shellac.  If  you  do,  it  will 
squeeze  out  into  the  interior  of  the  oil  casing  and  get  be- 
tween the  pins  and  the  cam,  thus  doing  serious  injury  to  the 
intermittent  movement.  Instances  have  been  known  where 
an  excess  of  shellac  has  broken  a  geneva  pin. 

No.  34.  Removing  Cam  Shaft  and  Cam, — First  follow  In- 
structions Nos.  21,  24,  25  and  33.  Then  loosen  the  two  set 
screws  in  the  collar  on  shaft  676,  P.  2,  just  above  arrow  head 
670,  P.  2,  move  the  collar  over  to  the  right  and,  with  a 
small,  fine  file,  smooth  off  the  burrs  caused  by  the  set  screws. 
The  shaft  and  cam  may  then  be  pulled  out  to  the  left. 

Caution:  In  replacing  this  shaft,  don't  forget  to  put  the 
collar  on. 


504 


MOTION    PICTURE   HANDBOOK 


No.  35.  To  Remove  Intermittent  Sprocket. — To  remove 
the  intermittent  sprocket,  follow  Instructions  19,  21,  24,  25, 
33,  and  34.  Next  loosen  screw  743,  P.  2,  and  the  entire 
sprocket,  its  shaft  and  the  large  left-hand  bushing  and  cross 
may  be  pulled  through  the  oil  well. 

No.  36.     Replacing  Intermittent  Sprocket. — This  is  a  thing 


739 


6A 


Plate  6,  Figure  246. 

I  by  no  means  advise  the  operator  to  attempt.  The  inter- 
mittent sprocket  of  a  projector  might  be  termed  the  "heart" 
of  the  machine.  It  is  imperative  that  the  sprocket  itself 
and  its  fitting  upon  the  shaft  be  accurate  within  one  ten- 
thousandth  of  an  inch.  It  is,  of  course,  possible  that  the 


FOR    MANAGERS   AND    OPERATORS 


505 


operator  might  fit  a  sprocket  to  the  shaft  in  such  way  that  it 
would  produce  perfect  results,  but  it  is  hardly  to  be  expected. 
I  would  by  all  means  advise  the  manager  to  purchase  an  extra 
cross,  shaft,  intermittent  sprocket  and  large  bushing,  assem- 
bled, and  all  ready  to  slip  into  the  machine.  Then,  instead  of 
taking  chances  on  fitting  a  sprocket,  you  can  slip  the  old 
one  out,  as  per  the  foregoing  instruction,  install  the  new  one, 
and  for  a  few  cents  send  the  old  one  to  the  factory  by 

617 
618 
613 
616 
614 


77 


Plate  7,  Figure  247. 

insured  parcel  post  and  have  a  new  sprocket  fitted  on  prop- 
erly, thus  insuring  perfect  results  on  the  screen.  In  this 
connection  see  last  part  of  General  Instruction  No.  5. 

I  would  go  further  than  this  and  recommend  to  the  theatre 
manager  that  he  purchase  a  complete  extra  framing  car- 
riage, so  that  in  event  of  wear  in  the  intermittent  movement, 


506  MOTION    PICTURE   HANDBOOK 

worn  intermittent  sprocket  teeth,  bushing  or  shafts,  the  en- 
tire framing  carriage  may  be  removed  (see  Instruction  No. 
37),  and  the  new  one  substituted.  You  may  then  send  the 
framing  carriage  to  the  factory  by  insured  parcel  post,  at  a 
merely  nominal  transportation  fee,  and  it  will  be  returned 
to  you  in  perfect  condition,  thus  insuring  you  against  any 
possibility  of  bad  results  on  the  screen  through  improper 
fitting  of  these  extremely  delicate  parts. 

No.  37.  Removing  the  Framing  Carriage. — To  remove  .the 
entire  framing  carriage  of  the  mechanism,  first  remove  the 
aperture  plate  (see  Instruction  No.  16)  and  the  gate  (see 
Instruction  No.  11).  Next  remove  screw  793,  P.  4,  in  top 
end  of  framing  lever  link,  turn  the  machine  around,  and 
looking  through  the  lens  hole  you  will  see  two  perpendicular 
rods,  the  top  ends  of  which  are  held  in  cast  lugs.  Loosen 
the  set  screws  in  these  lugs  and  in  similar  lugs  at  their 
lower  ends,  and  pull  these  perpendicular  rods  out  from  below. 
Next  remove  horizontal  bar  683,  P.  3,  by  taking  out  screw 
728,  P.  3.  The  carriage  may  then  be  taken  from  the  machine. 

No.  38.  Care  of  Sprockets. — (See  General  Instructions  Nos. 
3  and  4.) 

No.  39.   .Oil. — (See  General  Instruction  No.  1.) 

POWER'S  SIX  B,  SPEED  CONTROL 

The  entire  output  of  Power's  projection  machine  stands 
of  the  later  types  are  drilled  to  receive  the  Power's  Speed 
Control.  When  the  machine  is  received,  the  speed  control 


625  .^•^fe.      626         ^jgr 


FOR    MANAGERS   AND    OPERATORS  507 

parts,  as  shown  in  P.  1  and  2,  are  assembled,  with  the 
exception  of  the  lever  R  52,  Fig.  3,  but  the  control  is  not 
attached  to  the  stand.  To  attach  the  control,  place  same  in 
position,  as  shown  in  P.  1  and  2,  with  the  motor  toward  the 
rear  end  of  the  projector,  and  fasten  in  place  by  means  of 
bolts  R  5  (four  of  them),  P.  1  and  2.  Be  sure  that  the  con- 
tacts between  the  casting  and  the  control  are  clean,  and  set 
up  bolts  R  5,  tight.  This  instruction  holds  good  with  both  the 
old  style  6A  non-adjustable  and  the  new  style  6B  adjustable 
stand. 

It  is  then  necessary  to  attach  the  lever  control,  P.  3.  If 
it  is  the  old  style  6A  non-adjustable  stand  this  lever  and  its 
casting  is  attached  by  means  of  bolts  R  47  and  R  48,  P.  3.  If 
it  is  the  new  style  6B  adjustable  stand,  then  a  special  bracket, 
the  bottom  of  which  is  shown  at  X,  P.  1,  is  sent.  This 
bracket  is  attached  to  the  casting  by  means  of  two  heavy 
machine  screws,  one  of  which  is  shown  at  Z,  P.  1.  Having 
attached  the  control  lever,  all  that  is  necessary  to  complete 
the  installation  is  the'  connecting  of  lever  R  52,  P.  1,  with 
the  end  of  the  control  lever  at  R  42,  P.  3,  and  with  the  bell 
link  R  53,  P.  1. 

Note:  All  parts -except  very  small  screws  have  the  regular 
stock  number  either  stamped  or  cast  right  into  the  part — a 
very  excellent  arrangement.  Parts  may  be  ordered  by  using 
these  numbers.  All  inachihe  stands  are  drilled  to  receive 
the  speed  Control,  so  that  you  can  order  it  at  any  time,  and 
install  under  the  foregoing  instructions. 

Instruction  No.  1. — The  friction  material,  R  15,  P.  2,  is 
leather.  Should  it  at  any  time  develop  flat  spots,  or  become 
out  of  round  or  eccentric  in  form,  it  may  be  trued  by  placing 
the  point  of  a  new  10-inch  or  12-inch  coarse  file  on  rod  R  39 
(using  the*  rod  merely  as  a  rest)  and  bearing  lightly  on  the 
top  of  the  friction  material,  with  the  motor  running.  In  doing 
this,  be  very  careful  to  hold  the  point  of  the  file  perfectly  flat  on 
the  rod,  since  if  you  hold  it  at  an  angle  you  will  get  the  face  of 
the  leather  ground  off  on  a  slant,  and  it  will  then  not  fit  the 
disc  wheel  squarely. 

Instruction  No.  2. — New  friction  material  may  be  ordered 
from  the  Nicholas  Power  Company  at  any  time.  The  old 
material  may  be  removed  by  loosening  the  set  screws  in 
ihub  R  16,  P.  2,  and  in  set  collar  R  21  and  in  R  24,  P.  2, 
Having  done  this,  R  25,  P.  2,  may  be  pulled  out  to  the  right, 
thus  releasing  the  friction  wheel.  You  can  then  take  out 
the  old  friction  material  by  removing  the  screws  in  the  face 
of  R  16,  P.  2.  The  process  of  reassembling  is  the  reversal  of 


508 


MOTION    PICTURE    HANDBOOK 


the  process  of  disassembling,  but  these  parts  run  at  high 
speed,  therefore  be  sure  and  set  up  all  the  screws  tight. 

Instruction  No.  3. — Caution:  Never  leave  the  controlling 
lever  down  when  the  projector  is  standing  still.  Always  pull  the 
lever  clear  up,  so  as  to  disengage  friction  wheel  R  15,  P.  2, 
from  driving  disc  R  13,  P.  2.  Failure  to  attend  to  this  matter 
will  probably  result  in  flat  spots  on  the  friction  material.  In 
nine  cases  out  of  ten  where  flat  spots  develop  it  is  caused 
by  failure  to  heed  this  warning. 

Instruction  No.  4. — Tension. — It  is  of  course  necessary  that 
there  be  sufficient  tension  or  friction  between  friction  material 


Plate  1,  Figure  249. 

R  15  and  driving  disc  R  13,  P.  2,  to  pull  the  projection  mech- 
anism, but  anything  more  than  sufficient  to  accomplish  this 
purpose  will  merely  result  in  undue  wear  of  the  friction  disc, 
friction  material  and  unnecessary  consumption  of  power  in 
the  motor.  The  tension  or  amount  of  friction  between  fric- 
tion material  R  15  and  friction  disc  R  13,  P.  2,  is  regulated 
by  thumb  screw  R  32,  P.  1.  Proceed  as  follows: 

Loosen  lock  nut  R  33,  P.  1,  and  loosen  up  on  tension  screw 
R  32,  P.  1,  until  friction  material  R  15  and  disc  R  32  are  out 


FOR    MANAGERS    AND    OPERATORS 


509 


of  contact.  Now,  start  your  motor  running  and  having  set 
the  controlling  lever  down  so  that  the  friction  driving  wheel 
is  pretty  well  in  on  the  friction  disc,  slowly  tighten  up  on 
tension  screw  R  32,  P.  1,  until  the  projection  mechanism 
attains  full  speed  and  you  are  satisfied  there  is  no  slippage 
between  the  friction  disc  and  driving  wheel.  Having  done 
this,  your  tension  will  be  just  right,  provided,  of  course,  you 
have  followed  the  instructions  carefully,  and  have  set  up 


Plate  2,  Figure  250. 

screw  R  32  only  sufficient  to  bring  the  projector  up  to  full 
speed,  this  being  done,  of  course,  with  the  film  in  the  ma- 
chine, or  in  other  words,  under  actual  operating*  conditions. 
Having  got  the  adjustment  just  right,  don't  forget  to  tighten 
up  lock  nut  R  33,  or  else  the  adjustment  is  likely  to  work 
loose. 

Instruction  No.  5. — Grease  cups  (two  of  them),  P.  1,  should 
be  kept  filled  with  some  good  lubricating  grease  (not  oil  but 
grease),  which  may  be  obtained  from  any  automobile  supply 
store.  The  commutator  of  the  motor  can  be  got  at  by  open- 
ing the  two  latticed  cast-iron  doors  on  the  end  of  the  motor. 


510 


MOTION    PICTURE   HANDBOOK 


Instruction  No.  6.  —  The  motor  may  be  disengaged  merely 
by   removing  bolts   R  6,  P.  1   and  2,  and  disconnecting  its 

cable.  When  putting 
the  motor  back  be  sure 
and  line  the  shaft  of  the 
motor  correctly  with 
the  friction  driving  shaft 
R  25.  If  you  don't  do 
this,  -there  will  be 
trouble  and  probably 
more  or  less  noise.  In 
fact,  should  the  device 
develop  noise  at  any 
Plate  3,  Figure  251.  time>  and  you  find  that 

the  friction  wheel  ma- 

terial is  true,  then  the  next  thing  to  look  at  is  the  alignment 
of  these  two  shafts;  it  being  possible  that  bolts  R  8  have 
worked  loose  and  let  the  motor  get  out  of  alignment  with 
driving  shaft  R  25. 

Instruction  No.  7.  No  Oil.  —  With  the  exception  of  the 
motor  bearings,  none  of  the  other  bearings  of  this  device 
requires  any  lubrication  whatever,  this  by  reason  of  the  fact 
that  the  bushings  are  all  of  material  which  requires  no  lubri- 
cation. 

PARTS  FOR  POWERS  SIX  B  AND  MOTOR  DRIVE 

Order  parts  by  number.  Column  to  left  indicates  plate 
upon  which  they  appear. 


Plate    No. 

1  601     Main     frame    casting. 
3          602     Top   frame   casting. 

7         603     Frame   carriage. 

6  604     Top    frame    supporting 

rods   (2). 

3  &  5     605     Stero     bracket     holder 
with  thumb  screw. 

—  606     Stero     bracket     holder 

with  thumb  screw 

—  607     Stero  collar  bracket. 

—  608     Stero  lens  rod. 

2  609     Small  top  roller. 

7         610     Small  top  roller  spindle. 
2         611     Set     collar    for     small 

top    roller. 

2         612     Upper  roller  bracket. 
5         613     Large    upper  roller. 

7  614     Large       upper       roller 

spindle. 

2         615     Upper     roller     bracket 
spring. 


Plate    No. 
7         616 


7 

7 

1  &  4 


617 
618 
619 


1  &  4  620 

9  _  ,,  -„« 

3  &  7  623 

2  624 

—  625 

—  626 
7  627 


Set  collar  for  large  top 
roller. 

Upper  sprocket. 

Upper  sprocket  spindle 

Upper  sprocket  feed 
gear  (large). 

Upper  sprocket  feed 
gear  (small). 

Pinion  for  auto,  shut- 
ter spindle. 

Spindle  for  auto,  shut- 
ter. 

Friction  case  cover  for 
auto,  shutter. 

Friction  case  for  auto, 
shutter. 

Friction  shoe  with 
spring  flor  auto, 
shutter 

Weight  for  auto,  shut- 
ter. 

Lever  for  auto,  shutter. 


FOR    MANAGERS   AND    OPERATORS 


511 


Plate    No. 
7          628     Link  for  auto,  shutter. 

3  629     Counter       weight      for 

auto,    shutter. 

4  630     Crank      shaft      driving 

gear. 
4  &  7     631     Crank  shaft. 

7         632     Crank        shaft        with 
handle  complete 

4          633     Small  gear  meshing  in 
driving  gear. 

4          634     Large  gear  for  revolv- 
ing  shutter. 

4          635     Small   gear  for  revolv- 
ing  shutter. 

4         636     Spindle  for  front  shut- 
ter. 

4         637     Bracket    for    revolving 
shutter. 

4         638     Set     collars    for    front 
shutter  spindle    (2). 

—  639     Stud    with     screw     for 

front  shutter  bracket. 
4         640     Large  idler  gear. 

4  641     Idler       gear       spindle 

(large). 

5  642     Large  idler  gear  spindle 

set    collar. 

—  643     Take-up    feed    pinion. 

—  644     Take-up    feed    pulley. 

—  645     Take-up  feed  spindle 
2         646     Take-up  feed  sprockets 
4         647     Framing  device  clamp. 
4          648     Framing    lever    socket. 
4         649     Framing    lever    socket 

link. 
1         650     Framing   lever. 

—  651     Framing  device  screw. 
4         652     Framing    device    wing 

nut. 
1         653     Take-up  roller  bracket. 

—  654 

1  655     Take-up  roller  spindle. 
4         656     Set     collar     for     small 

spindle. 
2  &  4     657     Take-up  roller. 

2  658     Take-up  roller  bracket 

spring. 
2         659     Intermittent      roller 

bracket 
2         660     Intermittent   roller. 

—  661     Intermittent      roller 

bracket  spindles. 

—  662     Intermittent  set   collar 

for  shaft. 

—  663     Intermittent    spring. 

—  664     Contact       screws       for 

gauge. 

2         665     Intermittent    spindles. 

2         666     Pin    cross    (with    spin- 
dle). 

2         667     Intermittent    sprocket. 


2 

676 

7  &1 

677 

7 

678 

7 

679 

3 

680 

3 

681 

7 

682 

7  &3 

683 

8 

684 

7 

685 

7 

686 

Plate    No. 

—  668     Gate  spring  support. 

1  669     Apron  complete. 

2  670     Intermittent       bushing 

(large). 
1          671     Intermittent       bushing 

(small). 

5  &  3     672     Flywheel 
4          673     Oil  cup  int.  movement. 

4  614     Cover    for    int.    move- 

ment. 

—  675     Cam     for     int.     move- 

ment. 

Cam  shaft. 

Flywheel    pinion. 

Toggle  Joint  idler  gear. 

Toggle  joint  idler  gear 
spindle. 

Driving  gear  for  Idler. 

Driving   gear   spindle. 

Connecting   link. 

Small  horizontal  lever. 

Large    guide    casting. 

Small    casting. 

Studs     for     horizontal 
lever. 

Aperture    plate. 

Front   plate. 

Gate. 

Hinge   for  gate. 

Guide    rollers. 

Guide      rollers,      bush- 
ings,       spring       and 
spindle. 
1         693     Latch   for  door 

—  694     Tension    shoe. 

—  695     Gate   hinge    pin. 
1         696     Cooling  plate. 

1         69?     Flap  for  auto,  shutter. 

1  698     Rock  shaft  auto,   shut- 

ter. 

2  699     Carriage   guide   rods. 

6  700  Outside  revolving  shut- 
ter blade. 

6  701  Outside  revolving  shut- 
ter bushing  (large). 

6  702  Outside  revolving  shut- 
ter bushing  (small). 

6  703     Outside  revolving  shut- 

ter flange  complete. 

5  704     Lens   ring    screws. 
1         705     Upper   film   shield. 

7  706     Lower    film    shield. 

—  707     Spindles  for  lower  film 

shield. 

—  708     Lower        film        shield 

bracket. 

3  709     Flywheel  spindle  screw. 

—  710     Upper     roller     bracket 

screws  and  nut. 


512 


MOTION    PICTURE    HANDBOOK 


Plate 

No. 

Plate 

No. 

2 

711 

Screws  for  No.   658. 



741 

Springs   for   auto     K<>V- 

.  — 

712 

ernor   friction    shoe. 

2 

713 

Screws      for      aperture 

7 

742 

Set   screw   for  No.    679. 

plate. 

2 

743 

Screw  holding  No.   670. 

5 

714 

Lens  ring. 

7 

744 

Set    screws    to    tighten 

— 

715 

Screws    holding    inter- 

No.   682. 

mittent  roller  brack- 

7 

745 

Screws  holding  No.  685 

et. 

against   No.    682. 

— 

716 

Lower        film        shield 

7 

746 

Slots   in   No.    677. 

spring. 

7 

747 

Pins   to  engage   in   No. 

— 

717 

Screws    holding    take- 

746. 

up    bracket    spring. 

7 

748 

Washer     between     No. 

2 

718 

Screws      holding     gov- 

677 and  No     603. 

1  &  2 

719 

ernor  cover  to  shaft. 
Screws     adjust,     inter- 
mittent  shaft. 

4 

749 
750 

Oil  casing  cover  screws. 
Screws    holding    apron 

1 

720 

Screw      stud      holding 

No.   669. 

upper  roller  bracket. 

—  — 

751 

2 

721 

Screw     holding     upper 

— 

752 

Screw    top    end    of    No. 

sprocket   roller  spin- 

628. 

dle. 



753 

Screw      holding     upper 

2 

722 

Gate    latch    screw    and 

fire    shield. 

nut. 

5 

754 

Screw   holding  No.  688. 

1  &  2 

723 

Screw      holding      right 



755 

Screw    holding    tension 

hand  bushing  for  in- 

shoes. 

termittent  (No.  671). 



756 

4 

724 

Screw   to  adjust    lower 

757 

Hinge  screws. 

sprocket  rollers  with 

758 

Screws    holding     lower 

nut. 

fire  shield  bracket. 

— 

725 

Screw   holding  take-up 
roller  bracket. 

- 

759 

Screws     holding    roller 
idler         spindle         to 

— 

726 

Collars         for         lower 

bracket. 

bracket    spindle. 

7(50 

Screws  holding  top  end 

3 

727 

Screws       holding       top 

of  No     628. 

frame     casting     sup- 
port   rods. 

4 

7C1 

Loop   setter   cam. 

7 

728 

Screws     holding     hori- 
zontal lever. 

4 

702 
703 

Loop  setter  gear. 
Cam    pin    for   fork. 

3 

729 

Spring   for   gate    roller 

4 

764 

Loop        setter       pulley 

guide. 

shaft. 

4 

730 

Screws    holding    fram- 
ing   device    clamps. 

4 

4 

765 
766 

Loop    setter  pulley. 
Loop    setter   clutch. 

6 

731 

Stamp    on    wide    wing 

4 

767 

Loop   setter   bearing 

of   shutter. 

4 

768 

Loop  setter  fork. 

4 

732 

Upper     screw     holding 

3 

769 

Loop   setter   roller. 

revolving         shutter 



770 

Loop        setter         rollei 

bracket. 

washer. 

5 

733 

Lower     screw     holding 

4 

771 

Loop   setter  clutch    pin 

No.    637. 

(short). 

1 

734 

Screw     for     adjusting 

— 

772 

Loop   setter  clutch   pin 

tension   shoes. 

(long). 

6 

735 

Pin  through  No.  631. 

— 

773 

Loop    setter  arm   spin- 
dle 

5 

736 

Oil    hole    back    of   No. 
637. 

4' 

774 

Loop  setter  pulley  pin. 

5 

737' 

Magazine         thumb 

— 

775 

Loop     setter    stud    for 
bearing. 

2  &1 

738 

screws. 
Set  screws  for  sprocket. 

— 

776 

Loop   setter  clutch   pin 
for   fork. 

6 

739 

Screws    in    outer    shut- 

4 

777 

Loop        setter       pulley 

ter  hub. 

washer. 

740 


Screws  holding  No.  700 
to   shaft. 


—          778 


Loop    setter   set    screw 
for    roller    spindle. 


FOR  MANAGERS  AND    OPERATORS            513 

-  '779  Loop  setter  set  screw  ^^  187  Set  screw  and  nut  for 

for  cam  sate  stop. 

—  780  Loop  setter  set  screw  2  788  Screws  for  intermit- 
No  767  to  No.  601.  tent  spring. 

-         781     Loop  setter    set   screw  2         789     Screws  to  fasten  angle 


No     690   to  No.    601.  696   to   No-   689< 

— i         783     SJet     collar     for     inter- ^2 

'  mittent  shaft.  4          ?93     gcrew       for        take-up 

1          784     Screws    to    fasten    No.  roller   spindle 

•  '.705   to   No.    689.  4        ''794     Screw     for     cover     No. 

7         785     Screws    to    fasten    No.  674  to  No.    603    (car- 

628  to  No.  601.  riage). 

7         786     Set    screws    for  handle  2          795     Pins    for    No.    631. 

j  No.    632.  3          796     Screws  to  hold  No.   641 


Instructions  for  Simplex  Mechanism 

Note:  Tjhe  numbers  refer  to  parts  and  plates,  thus: 
W-128-B,  P.  4,  means  that  part  W-128-B,  which  by  reference 
to  the  list  of  parts,  we  find  to  be  the  fly  wheel  of  the  inter- 
mittent movement,  will  be  found  on  Plate  4. 

No.  1.  $&  Remove  the  Film  Trap  Door,  E  4,  P.  5,  lift  it 
straight'  upward,  unhooking  the  vdoor  from  pins.  The  door 
will  disengage  when  raised.  Should  it  stick  tap  upward 
lightly  on  bottom  of  door. 

No.  2.  To  Remove  Intermittent.— To  take  out  whole  in- 
termittent movement,  remove  screw,  S-209-G,  P.  3,  pull  off 
gear,  G-112-G,  P.  3.  Push  in  on  film  trap  screw,  S-134-E, 
P.  2,  which  opens  door.  -  Next  remove  o  pull  back  the  lower 
right  hand  back  section  of  machine — the  door  with  the 
curved  top  immediately  .below  the  aperture.  Next  loosen 
screws,  S-157-B,  P.  2  and  4,  and  push  back  locks,  L-116-B, 
P.  4,  so  that  they  no  longer  engage  ring,  R-133-A,  P.  1,  on 
framing  cam,  C-100-A,  P.  1  and  4.  Loosen  collar,  C-192-G, 
P.  !5,  grasp  fly  wheel,  W-128-B,  P.  3,  with  right  hand,  and 
pull  straight  outw.ard,  at  the  same  time  pulling  out  gear, 
G-133-Gi,  P.  3,  with  the  left  hand.  You  thus  remove  the  entire 
intermittent  casing,  fly  wheel  and  intermittent  sprocket.  In 
replacing  same,  reverse  the  process  of  removal  step  by  step, 
first  reading  Instruction  No.  8  carefully. 

No.  3.  Adjusting  Star  and  Cam  (See  last  part  of  General 
Instruction  No.  5)  is  done  as  follows:  Loosen  two  screws, 
S-125-B,  P.  4.  Grasp  hexagon  on  B-132-B,  P.  4,  with  the 
wrench  supplied  with  each  machine,  or  with  a  plier,  and 
turn  same  slightly  either  way  until  the  lost  motion  in  the 
sprocket  is  almost  taken  up,  leaving  just  enough  play  so  that 


514 


MOTION    PICTURE    HANDBOOK 


you  can  barely  feel  the  sprocket  move  when  you  try  to  rock 
it  circumferentially.  Tighten  screws  (two  of  them),  S-125-B, 
P.  4,  when  you  are  finished. 


Figure  252. 


No.  4.    Removing  and  Replacing  Intermittent  Sprocket.— 

(I  do  not  recommend  it.     See  last  part  General  Instruction 


FOR    MANAGERS   AND    OPERATORS  515 

No.  5.)  When  the  sprocket  teeth  become  undercut,  that  is  to 
say,  having  a  groove  worn  in  the  surface  presented  to  the 
film,  the  sprocket  should  be  removed  and  a  new  one  installed, 
(it  is  a  good  plan  to  have  an  eccentric  bushing,  B-132-B,  P.  4 
and  5,  star  and  spindle,  S-299-B,  P.  5,  and  intermittent  sprocket, 
W-131-B,  P.  1,  already  assembled,  ready  to  place  in  the  ma- 
chine when  required)  this  being  done  as  follows:  Loosen  the 
two  screws,  S-125-B,  P.  4,  and,  grasping  intermittent  sprocket, 
pull  straight  out,  thus  removing  bushing,  star,  spindle  and 
sprocket  from  the  casing.  Next  carefully  remove  sprocket 
from  spindle.  To  do  this  first  remove  taper  pin  which  holds 


Figure  253. 

Showing   the    relation   of   the   parts  of   the   Intermittent  movement,   a 
portion  of  the   casing  being  cut  away  to   show  you  the  parts  in  place. 

the  sprocket  to  the  shaft,  and  with  a  cloth  in  the  left  hand 
grasp  star  and  bushing  firmly,  while  with  the  right  hand  you 
pull  the  sprocket  from  its  spindle  with  a  twisting  motion. 
Should  the  sprocket  stick  you  may  lay  the  edges  on  a  vise 
and  with  a  brass  or  copper  punch  gently  drive  the  spindle 
out.  Be  very  careful,  if  the  sprocket  is  good,  that  you  do 
not  ruin  it  in  the  process,  as  its  rim  is  thin  and  easily 
battered  or  bent.  In  installing  the  new  sprocket  be  very 
sure  that  the  large  diameter  of  the  pinholes  in  shaft  and 
sprocket  are  together.  To  replace  parts  in  the  machine, 
first  wipe  the  bushing  and  its  bearing  parts  perfectly  clean 
and  lubricate  with  good  clean  oil.  Push  the  bushing  into  its 
bearings  until  the  star  is  against  the  cam;  turn  the  fly  wheel 
slowly,  at  the  same  time  pushing  in  on  the  sprocket  until 
pin,  P-177-B,  P.  5,  on  cam,  C-178-B,  P.  5,  engages  with  star 
slot,  when  bushing  may  be  pushed  home;  after  which  adjust 


516 


MOTION    PICTURE    HANDBOOK 


star  to  cam  as  per  Instruction  No.  3  and  tighten  up  the  two 
screws,  S-125-B,  P.  4.  See  Instructions  Nos.  10  and  11. 

No.  5.    Cleaning  Sprockets — See  General  Instruction  No.  3. 

No.  6.  End  Play  of  Intermittent. — See  General  Instruc- 
tion .No.  7. 

No.  7.  To  Remove  Intermittent  Casing  Cover,  C-148-B, 
P.  4  and  5,  first  follow  instruction  Nos.  2  and  4,  next  in- 


,W-IZ6-D 

TH26-R 

M  12-R 

S-IOl 

Oil 

C-IOO-A 

W-I06-G 

N-IO5-G 

S-34I-G 

B-IOO-A 


Plate  1,  Figure  254. 

sert  spanner  wrench  in  hole  on  C-148-B,  P.  4,  and  unscrew 
the  cover  from  casing.  The  screw  on  this  cover  is  an  ordi- 
nary right  hand  thread.  See  Instructions  Nos.  10  and  11. 

No.  8.  To  Remove  Cam,  C-178-B,  P.  5,  first  follow  In- 
structions Nos.  2,  4  and  7;  then  remove  taper  pin  holding 
collar,  C-134-B,  P.  4,  and  pull  collar  off.  The  cam  and.  its 


FOR    MANAGERS   AND    OPERATORS  517 

spindle  may  then  be  pulled  out.  See  Instructions  No.  10 
and  11. 

No.  9.  To  Remove  Flywheel  Shaft,  S-286-B,  P.  3,  first  fol- 
low Instructions  Nos.  2,  4,  7  and  8;  then  drive  out  taper  pin, 
P-123-B,  P.  3,  pull  off  flywheel  and  shaft  will  slip  out.  See 
Instructions  Nos.  10  and  11. 

No.  10.  Replacing  Bushing,  B-132-B,  P.  4  and  5,  and  In- 
termittent Casing,  C-107-B,  P.  4  and  5.  This  is  a  very  simple 
operation.  It  is,  however,  of  great  importance  that  it  be 
rightly  done.  Both  the  casing  and  bushing  fit  in  their  bear- 
ings very  closely.  It  is  therefore  necessary  that  they,  as 
well  as  their  bearings,  be  cleaned  perfectly  and  lubricated 
with  a  good,  clean  oil.  Having  done  this,  push  the  casing 
or  bushing  carefully  into  place,  turning  or  shaking  it  slightly 
if  it  sticks.  Never  under  any  circumstances  attempt  to 
drive  the  parts  into  place.  You  will  simply  ruin  both  bear- 
ings and  casings,  or  bushings,  if  you  do. 

No.  11.  To  Replace  Intermittent  Casing,  C-107-B,  P.  4  and 
5,  in  the  machine,  first  follow  Instruction  No.  10;  then  hold 
flywheel,  W-128-B,  P.  3  and  4,  in  right  hand,  and  gear,  G-133- 
G,  P.  3  and  4,  in  left  hand  with  gears  meshed  together;  in- 
sert shaft  and  casing,  C-107-B,  P.  4  and  5,  into  bearings  and 
push  both  casing  and  gear  into  place  together,  having  the 
rim  of  casing  in  such  position  that  locating  pin,  P-12S-A,  P.  4, 
enters  hole  in  casing  rim.  The  rest  of  the  operation  is 
simply  a  reversal  of  Instruction  No.  2.  See  that  the  clutch, 
C-126-A,  P.  4,  locks  with  its  mate  properly  when  gear,  G-112- 
G,  P.  3  and  4,  is  pushed  into  place. 

No.  12.  To  Remove  Gear,  G-143-G,  P.  4,  or  the  complete 
Governor  or  Vertical  Shaft,  S-443-G,  P.  4,  loosen  set  screw 
in  hub  of  gear  G-143-G,  P.  4,  next  remove  set  screw  in 
governor  ling  holder  and,  grasping  gear  G-138-G,  P.  4,  pull 
upward.  Vertical  shaft,  S-443-G,  P.  4,  will  come  out,  thus 
releasing  the  other  parts. 

No.  13.  To  Remove  Spiral  Gear,  G-116-G,  P.  4,  first  follow 
Instruction  No.  12;  then  remove  set  screw  holding  collar, 
C-193-G,  P.  5,  and  pull  shaft  out  to  the  right. 

No.  14.  To  Remove  Spiral  Gear,  G-117-G,  P.  4,  remove  set 
screw  from  end  of  gear.  Spindle  will  slip  out  to  the  left, 
thus  releasing  gear. 

No.  15.  To  Remove  Shutter  Gear  Bracket,  B-122-G,  P.  2 
and  3,  first  follow  Instruction  No.  14;  then  remove  the  two 
screws,  and  bracket  will  come  off. 

No.  16.    To  Remove  Shaft  of  Outside  Revolving  Shutter, 


518 


MOTION    PICTURE    HANDBOOK 


S-447-G,  P.  2,  remove  the  set  screw  from  gear,  G-117-G,  P.  4, 
and  shaft  may  be  pulled  out. 

No.  17.    To  Remove  Shutter  Blade  take  out  the  ten  screws, 
S-142-D,  P.  2,  in  spider,  S-325-D,  P.  2. 


H-I25-C 
P-429-C 
IO3-C 
S-J44-G 
S-252-A 
S-253-A 
S-I93-C 
A-I08-D 


Plate  2,  Figure  255. 

No.  18.  To  Remove  Shutter  Adjusting  Slide  Block,  S-323- 
A,  P.  2,  remove  pin  near  outer  edge  of  lower  track  or  slide, 
and  turn  the  knob,  K-lll-A,  P.  2,  to  the  left  until  sliding 
block,  S-323-A,  P.  2,  is  released. 

No.  19.    To  Remove  Shaft  or  Screw,  S-252-A,  P.  2,  loosen 


FOR    MANAGERS   AND    OPERATORS  519 

lock  nuts,  123-A,  P.  2,  turn  knob  to  left  until  sliding  block, 
S-323-A,  P.  2,  is  released.  Remove  the  lock  nuts  and  the 
shaft  may  be  pulled  out. 

No.  20.  To  Remove  Focusing  Slide,  which  carries  lens 
holder  H-125-C,  P.  2,  remove  the  screw  which  holds  same  to 
frame,  F-100-A,  P.  1,  and  the  slide  will  come  out.  On  top 
there  will  be  found  a  small  gib  which  provides  tension.  Be 
sure  to  replace  this  gib  when  putting  the  parts  together 
again. 

No.  21.  To  Remove  Framing  Cam,_  C-100-A,  P.  1  and  4, 
take  out  upper  screw,  S-223-G,  P.  3.  ^Remove  door,  as  per 
Instruction  No.  1.  Remove  screws,  S-133-C,  P.  4,  which 
releases  the  film  trap.  Loosen  screws,  S-143-A,  P.  5,  un- 
screw ring  and  the  cam  may  then  be  pulled  out  to  the  left.  The 
framing  cam,  C-100-A,  P.  1  and  4,  is  a  large  ring  bearing  in 
which  the  intermittent  casing,  C-107-B,  P.  4  and  5,  rests.  To 
replace  same,  just  reverse  the  process,  screwing  up  ring  un- 
til cam  has  no  end  play,  after  which  set  up  screw,  S-143-A, 
P.  5,  tight,  as  this  is  the  screw  Which  locks  ring  in  place. 

No.  22.  To  Remove  Automatic  Fire  Shutter  Lift  Lever, 
first  remove  screw  in  link.  Next  remove  film  trap,  as  per 
Instruction  No.  1,  and  take  out  pivot  screw. 

No.  23.  To  Remove  Governor  Lift  Lever,  L-105-G,  P.  4, 
remove  lower  screw  in  link,  and  screws,  S-150-G,  P.  4. 

No.  24.  To  Remove  Framing  Slide  Lever,  L-104-G,  P.  3, 
first  remove  gears,  G-112-G,  P.  3  and  4,  and  G-133-G,  P.  3  and  4, 
and  intermittent  casing,  as  per  Instruction  No.  2.  Loosen  screw, 
S-145-G,  P.  3,  which  allows  you  to  pull  out  lever,  L-104-G, 
P.  3,  carrying  spring,  S-330-G,  P.  3,  with  it.  This  also  re- 
leases framing  slide  arm,  A-110-G,  P.  4,  carrying  roller,  R- 
128-G,  P.  4,  which  may  be  pulled  out  after  lever,  L-104-G,  P. 
3,  has  been  removed. 

No.  25.  Spring,  S-330-G,  P.  3.  This  spring  is  for  the  pur- 
pose of  holding  roller,  R-128-G,  P.  4,  against  the  framing  cam, 
C-100-A,  P.  4.  It  also  holds  lost  motion  out  of  parts  between 
lever  and  framing  cam.  To  remove  the  spring  take  out 
screw,  S-145-G,  P.  3,  which  releases  the  spring.  To  replace, 
put  it  on  its  stud  in  same  position  as  it  was,  then  bend  the 
free  end  around  to  the  right  until  it  enters  slot  in  end  of 
stud.  Place  washer  on  and  replace  screw,  S-145-G,  P.  3, 
setting  it  up  tight. 

No.  26.  Framing  Handle  Tension  Spring,  S-341-G,  P.  1. 
This  spring  causes  framing  handle,  or  lever,  H-105-C,  P.  3,  to 
work  hard  or  easy,  according  to  how  it  is  adjusted.  If  lever, 


520 


MOTION    PICTURE   HANDBOOK 


H-105-G,  P.  3,  works  too  hard,  this  spring  has  too  much 
tension:  if  too  easy  there  is  not  enough.  To  change  the 
tension,  first  remove  screw,  S-209-G,  P.  3,  and  pull  off  gear 
G-112-G,  P.  3.  Loosen  outer  one  of  nuts  and  tighten  or 


K-I02-A 
S-I46-A 
G-I03-G 
P-I89-A 
B-I27-A 
H-I21-G 
W-126-D 


L-I07-G 
A-M8-6 


Plate  3,  Figure  256. 

loosen   inside  nut  until  the  lever  works   to   suit  you,   after 
which  lock  the  nuts  lightly  together  again. 

No.  27.  Film  Trap  Door  Holder,  H-119-E,  P.  2  and  5,  is 
held  in  place  by  film  trap  door  holding  stud,  S-367-E,  P.  2 
and  5,  which  runs  through  and  is  held  by  a  screw  on  the 


FOR    MANAGERS   AND    OPERATORS  521 

outside  which  also  retains  a  thimble,  inside  of  which  is  a 
coil  spring,  which  holds  the  door  against  film  trap.  All 
these  parts  may  be  readily  removed  as  follows:  Place  a 
piece  of  cloth  or  paper,  between  the  jaws  of  a  pair  of  pliers 
t:>  prevent  marring  the  metal,  and  unscrew,  thus  releasing 
the  spring  and  stud,  S-367-E,  P.  2  and  5.  The  metal  thimble 
on  screw,  S-134-E,  P.  2,  is  merely  to  protect  and  hold  the 
coil  in  proper  position.  If  it  is  desired  to  remove  the  door 
holder  and  stud  also  you  must  take  off  film  trap.  (See  In- 
struction No.  1.) 

No.  28.  Film  Trap  Shoes,  S-309-E,  P.  5,  may  in  time  wear. 
(See  General  Instructions  Nos.  9  and  10.)  They  may  be  re- 
moved by  taking  out  the  three  screws  in  front  of  the  film 
trap  which  holds  them  in  place.  Should  the  screws  project 
through  when  new  shoes  are  installed,  they  must  be  carefully 
dressed  down  flush  with  surface  of  the  film  trap,  using  a 
fine  file,  this  also  applying  to  film  trap  gate  shoes. 

No.  29.  Intermittent  Sprocket  Tension  Shoes  attached  to 
holder,  H-118-E,  P.  5,  are  made  of  tool  steel.  They  hold  the 
film  in  contact  with  intermittent  sprocket,  W-131-B,  P.  1;  their 
adjustment  is  therefore  important.  They  must  be  set  so 
that  their  curved  portion  just  barely  touches  th6  sprocket 
rim.  It  must,  however,  be  observed  that  the  inside  half  of 
each  shoe  is  offset  so  that  it  is  away  from  the  sprocket 
slightly  when  the  outer  edge  touches.  Set  by  the  outer  half 
only.  Look  at  the  shoes  occasionally  and  see  that  they  are 
in  proper  adjustment. 

No.  30.  Lens  Holder,  H-125-C,  P.  2,  may  be  shifted  for- 
ward or  backward  on  sliding  block,  by  loosening  clamp 
screw.  In  installing  new  lens,  place  sliding  block  in  center 
of  its  travel  by  means  of  focusing  knob,  K-102-A,  P.  3. 
Place  lens  in  adapter  ring.  These  rings  are  made  to  fit  vari- 
ous sizes  of  lenses.  Loosen  clamp  screw,  and  slide  lens 
back  and  forth  until  edges  of  aperture  appear  in  sharp  focus 
on  the  screen.  Tighten  clamp  screw  and  complete  focusing 
by  means  of  knob,  K-102-A,  P.  3.  Tube  projection  lenses 
only  may  be  used  on  the  Simplex  machine.  It  is  therefore 
unnecessary  to  purchase  a  lens  jacket. 

No.  31.  Upper  and  Lower  Sprocket  Roller,  P-102-C,  P.  2, 
(See  General  Instruction  No.  12),  must  be  carefully  ad- 
justed with  relation  to  the  sprockets.  The  upper  roller  is  ad- 
justed by  means  of  screw,  S-194-C,  P.  2,  That  of  the  lower 
idler  is  adjusted  by  a  similar  screw,  S-194-C,  P.  2,  These 
rollers  must  be  kept  set  away  from  the  sprockets  by  about 


522 


MOTION    PICTURE    HANDBOOK 


twice  the  thickness  of  a  film.  If  set  too  close  it  has  a  ten- 
dency to  cause  the  film  to  run  off  the  sprockets.  If  too  far 
away  it  may  cause  the  sprocket  holes  to  climb,  that  is,  the 
film  may  slip  over.  In  either  event  the  effect  is  to  lose  the 
loop.  It  will  be  seen  that  these  adjustments  are  of  the 


C-J26-A 


Plate  4,  Figure  257. 


utmost   importance.     After  making   adjustment   be    sure    to 
set  up  the  adjusting  screw  lock  nuts  tightly. 

No.  32.  Roller  Arm  Tension  Springs.— Upper  sprocket 
roller  arm,  A-126-C,  P.  2,  is  held  against  sprocket  by  means 
of  a  spring  clamped  under  screw,  S-149-A,  P.  2.  To  remove 
this  spring,  take  off  film  trap,  as  per  Instruction  No.  1.  The 
lower  roller  arm  spring,  S-340-A,  P.  5,  is  held  by  two  screws 


FOR   MANAGERS   AND    OPERATORS 


523 


Which  may  be  removed  through  the  opening  in  base,  B-100-A, 
P.  1,  of  the  machine. 

No.  33.  Aperture  Size. — The  Simplex  aperture  opening  is 
exactly  .9062  inch  wide  by  .6796  inch  high,  the  height  being 
three-quarters  of  the  width.  These  dimensions  may  be  used 
in  figuring  lenses  for  this  machine. 


S-309-E 


-162-D 


lS-326-E 


Plate  5,  Figure  258. 


No.  34.  Oil. — (See  General  Instruction  No.  1.)  Also  the 
Precision  Machine  Company  sells  Simplex  Oil  at  $2  a  gallon, 
$1  a  half  gallon. 

No  35.  Washing  Gears  and  Bearings. — Simplex  gears  and 
bearings  are  well  protected  from  dust  and  dirt.  Still,  it  is 
not  a  bad  plan  to  wa^h  them  thoroughly  with  kerosene  or 
benzine  once  each  week.  Use  an  ordinary  oil  can  filled  with 


524  MOTION    PICTURE    HANDBOOK 

kerosene  or  benzine  and  flood  the  gears  and  bearings 
thoroughly  while  turning  the  crank.  Use  rags  under  the 
gears  to  catch  the  dirty  oil  as  it  runs  off.  See  third  from 
last  paragraph  General  Instruction  No.  1. 

No.  36.  Setting  the  Shutter.— (See  General  Instruction  No. 
18.)  The  revolving  shutter  may  be  set  while  the  machine  is 
running  by  turning  knob,  K-lll-A,  P.  2.  If  white  streaks 
show  at  top  or  bottom  of  letters  in  titles  or  there  are  flashes 
of  white  up  and  down  from  any  white  object  in  film  it  is 
evident  that  the  shutter  is  out  of  adjustment.  Turn  knob, 
K-lll-A,  P.  2,  one  way  or  the  other  until  the  ghost  dis- 
appears. 

No.  37.  Focusing  Lens. — The  picture  on  the  screen  is 
readily  focused  by  turning  knob,  K-102-A,  P.  3,  which  moves 
the  objective  lens  closer  to  or  further  from  the  film,  accord- 
ing to  the  way  it  is  turned. 

No.  38.    Clean  Sprockets.   (See  General  Instruction  No.  3.) 

No.  39.  Tension  Pad,  P-100-E,  P.  5,  holds  the  film  flat  and 
stationary  over  the  aperture  during  exposure.  Tension  for 
pad,  P-100-E,  P.  5,  is  provided  by  spring,  S-328-E,  P.  2  and  5. 
The  tension  is  constant  and  can  only  be  varied  by  bending 
th*  springs.  (See  General  Instruction  Nos.  9  and  10.) 

No.  40.  Stereopticon  Lens. — The  stereo  lens  will  be  placed 
in  its  mount  and  clamped  there  by  a  ring,  R-112-R,  P.  1. 
To  adjust  lens  loosen  wingnuts,  S-155-D,  P.  1,  and  slide  the 
lens  and  mount  either  forward  or  backward  on  rod,  R-126-R, 
P.  1,  until  picture  is  in  approximate  focus  on  screen.  Tighten 
wingnuts,  S-15S-D,  P.  1,  again  and  complete  focusing  with 
knob  on  top  of  mechanism,  K-102-A,  P.  1.  The  stereo  lens 
may  be  raised  or  lowered  by  means  of  screw,  S-264-D,  P.  1, 
on  stero  arm,  A-122-D,  P.  1,  thus  centering  the  picture  on 
the  screen. 

No.  41.  Oil  Holes  will  be  found,  as  indicated  on  the  vari- 
ous plates. 

No.  42.  Worn  Aperture  Plate.— See  General  Instruction 
No.  11. 

SIMPLEX  SPEED  CONTROLLER 

The  speed  controller  of  the  Simplex  projector  is  simple, 
positive  in  its  action,  and  very  flexible  in  the  matter  of  speed 
control.  In  fact,  within  the  limits  of  minimum  and  maximum 
it  is  possible  instantly  to  attain  absolutely  any  desired  speed 
of  the  projection  mechanism  within  practical  limits  of  pro- 
jection. 


FOR    MANAGERS    AND    OPERATORS  525 

In    Fig.   259  we   have   a   top  view   and   in   Fig.   260  a  side 
eiew  of  the  Simplex  Controller;   X-7  and  D-110-X  are  two 


Figure  259. 

friction  discs  held  normally  face  to  face  by  spring  S-470-X, 
but  really  held  separated  by  disc  wheel  X-8,  which  is  carried 
by  shaft  S-475-X,  which  engages  with  and  drives  the  projec- 
tion mechanism.  The  operation  is  essentially  as  follows: 
R-152-X  is  a  steel  bar  half  inch  square,  which  is  rigidly 
attached  to  the  casting  carrying  wheel  X-ll,  and  disc  wheels 
X-7,  and  D-110-X.  All  these  parts  are  attached  rigidly  to 
.bar  R-152-X,  and  move  therewith,  as  does  also  casting  X-3 
at  the  other  end  of  the  bar  carrying  the  end  belt  idler  pulley 
P-248-X. 

On  the  other  hand  casting  F-115-X,  Fig.  260,  carries  fric- 
tion disc  wheel  X-8,  adjusting  wheel  X-9  and  the  inner  idler 
belt  "pulley  P-248-X.  This  casting  carrying  the  parts  is 
moved  along  on  bar  R-152-X  by  means  of  adjusting  wheel 
X-9,  and  when  it  is  moved  friction  wheel  X-8  is  thrust  far- 
ther in  between  friction  discs  X-7  and  D-110-X,  or  pulled 
further  out,  according  to  the  direction  in  which  adjusting 
wheel  X-9  is  rotated,  and  the  farther  in  wheel  X-8  is  the 
slower  will  the  moving  picture  mechanism  run,  or  the  far- 
ther out  it  is  the  faster  it  will  run,  X-ll  being  the  motor 
belt  pulley. 

The  amount  of  friction  between  the  disc  wheels  may  be 
regulated  by  means  of  nuts  N-136-X.  The  farther  in  they  are 
screwed  the  greater  will  be  the  amount  of  friction,  or  the 
more  they  are  loosened  up  the  less  the  friction.  The  friction 


526 


MOTION    PICTURE    HANDBOOK 


should  never  be  more  than  just  sufficient  to  carry  the  load 
without  slipping.  Anything  in  excess  of  this  means  unneces- 
sary wear  to  the  parts. 

Caution:  Operators  must  see  to  it  that  there  is  no  oil  on 
the  friction  surfaces  of  X-8,  X-7  and  D-110-X.  These  sur- 
faces must  be  kept  perfectly  dry. 


F-I15-X 


Figure  260. 

C-141-X  is  an  oilhole  closed  by  a  steel  ball.  Press  on  the 
ball  with  the  nose  of  the  oil  can  and  the  oil  will  run  in. 
Spring  S-471-X  merely  governs  the  tension  of  the  driving 
belt. 

SIMPLEX  MECHANISM  PARTS 

Numbers  Are  Manufacturers'  Stock  Numbers.    You  May  Use 
These   Numbers   for   Ordering   Parts. 

Note. — The  letter  following  the  number  denotes  the  portion 
of  the  mechanism  to  which  the  part  belongs,  thus:  A,  Center 
Frame  Assembly;  B,  Intermittent  Case  Assembly;  C, 
Mechanism  Assembly;  D,  Outside  Mechanism  Assembly; 
E,  Film  Trap  Assembly;  F,  G,  Inside  Mechanism.  Hence  if 
you  are  looking  for  a  part  belonging  to  the  film  trap  as- 
sembly, look  at  the  part  numbers  ending  in  E. 

Plate    Stock 

No.        No.  Description 

1     C-189-A    Handle    shaft    driv- 
ing   collar. 
1     F-100-A    Centre  frame. 

1  K-102-A    Focusing     pinion 

knob. 

2  K-lll-A    Shutter        adjusting 

screw    knob. 


Plate    Stock 

No.        No.  Description. 

3     A-109-A   Focusing  rack  arm. 
3     A-117-A    Picture  framing-arm. 
1     B-100-A    Base. 

3  B-127-A    Vertical         shaft 

bracket. 
1     C-100-A    Framing  cam. 

4  C-126-A    Main    driving     gear 

Clutch. 


FOR    MANAGERS   AND    OPERATORS 


527 


Plate    Stock 
No.        No. 

1  N-118-A 

2  N-123-A 
4  P-125-A 
1  P-136-A 

3  P-189-A 

4  P-196-A 

1  R-133-A 

5  S-143-A 
3  S-146-A 

2  S-149-A 
2  S-252-A 

2  S-253-A 

3  S-283-A 


1  S-287-A 

2  S-323-A 

5  S-340-A 

2  S-353-A 

4  B-132-B 

4  C-107-B 

4  C-134-B 

5  C-148-B 

5  C-178-B 

4  G-104-B 

5  G-105-B 

4  L-116-B 

3  P-123-B 
2  P-134-B 

5  P-177-B 

4  S-125-B 

5  S-130-B 

2  S-157-B 

3  S-286-B 
5  S-299-B 
3  W-128-B 
1  W-131-B 

5  A-100-C 

5  A-104-C 


Description. 

Picture    framing 
handle    pivot  nut. 

Shutter        adjusting 
screw   lock  nut. 

Framing    cam    loca- 
ting   pin. 

Inter-sprocket  wheel 
taper    pin. 

Focusing   pinion. 

Picture    framing 
handle  pivot. 

Framing     cam     ad- 
justing   ring. 

Framing     cam     ad- 
justing ring  screw. 

Focusing     knob     set 
screw. 

Upper  sprocket  arm 
spring     screw. 

Shutter       adjusting 
screw. 

Shutter        adjusting 
slide   set  screw. 

Vertical  shaft  brack- 
et screw. 

Handle  shaft. 

Shutter        adjusting 
slide. 

Lower  sprocket  roll- 
er   arm    spring. 
Upper  sprocket  roll- 
er   arm    spring. 

Eccentric    bushing. 

Intermittent  case. 

Star       wheel       cam 
collar. 

Intermittent        case 
cover. 

Star  wheel   cam. 

Fly   wheel    gear. 

Fly       wheel       shaft 
gear. 

Intermittent     case 
cover  lock. 

Fly  wheel  taper  pin. 

Intermittent     case 
cover   dowel   pins. 

Star  wheel  cam  pin. 

Intermittent  case  ec- 
ccentric   bush.    sc. 

Film     guide     holder 
screw. 

Intermittent     case 
cover  lock  screw. 

Fly   wheel    shaft. 

Star  wheel  and  shaft. 

Fly  wheel. 

Intermittent  sprock- 
et wheel. 

Proj.      lens      holder 
adapter,   inside 

Proj.      lens      holder 
adapter,  outside. 


Plate    Stock 
No.        No. 


2 

A-115-C 

2 

A-126-C 

5 

C-4 

3 

H-105-C 

2 

2 

H-125-C 
L-103-C 

4 

L-110-C 

4 

L-lll-C 

5 
1 

P-102-C 
S-101-C 

4 

2 

S-133-C 
S-193-C 

2 

S-194-C 

2 

S-201-C 

2 

2 

S-217-C 
S-226-C 

5 

S-227-C 

2 

S-322-C 

2 
1 
2 
5 
1 

A-108-D 
A-122-D 
H-10'9-D 
P-207-D 
P-209-D 

1 

S-124-D 

1 

S-155-D 

2 

S-162-D 

2 

S-198-D 

1 

S-264-D 

5      S-279-D 

1  S-324-D 

2  S-325-D 
2      S-366-D 

2  W-103-D 

3  W-126-D 
5    W-145-D 
2    W-146-D 
5     E-4 

1  E-5 

5     H-118-E 

2  H-119-E 

1     L-101-E 


Description 

Lower  sprocket  roll- 
er arm. 

Upper  sprocket  roll- 
er arm. 

Film       trap       lever, 
complete. 

Picture    framing 
handle. 

Proj.   lens  holder. 

Film  trap  door  trip 
lever. 

Governor    lift    lever 
link. 

Governor    lift    lever 
connecting    link. 

Pad    roller. 

Auto      fire     shutter 
hinge  screw. 

Film    trap   screw 

U.     &     L.     sprocket 
roller   arm   screw. 

Lower  sprocket  roll- 
er  arm   screw. 
Proj.       lens       holder 
jacket  screw. 

Pad   roller  screw. 

Proj.      lens      holder 
clamp   screw. 

Proj.      lens      holder 
slide  stop  screw. 

Proj.      lens      holder 
slide 

Driving    arm. 

Stereo    slide  arm. 

Driving  arm  handle. 

Top    plate. 

Driving  arm  retain- 
ing plug. 

Driving  arm  retain- 
ing screw. 

Stereo  universal 

clamp  wing  screw. 

Stereo       slide       top 
screw. 

Shutter  spider  clamp 
collar  screw. 

Stereo    lens    adjust- 
ing   screw. 

Top  plate  screw. 

Stereo   slide. 

Shutter  spider. 

Driving   arm    stud. 

Driving  arm  washer. 

Governor    weight. 

Upper  sprocket. 

Lower  sprocket. 

Film  trap  door. 

Film  heat  shield. 

Film  guide  holder. 

Film  trap  door  hold- 
er. 

Auto      flre      shutter 
lift  lever. 


528 


MOTION    PICTURE    HANDBOOK 


Plate    Stock 

Plate    Stock 

No. 

No. 

Description. 

No. 

No. 

1 

L-109-E 

Auto      fire      shutter 

4 

G-138-G 

lift  link. 

4 

G-142-G 

5 

P-100-E 

Film  trap  door  pad. 

4 

G-143-G 

2 

P-214-E 

Film  protector. 

3 

H-121-G 

1 

R-130-E 

Lateral  guide  roller. 

1 

S-100-E 

Auto      fire      shutter 

3 

L-104-G 

lever    screw. 

4 

L-105-G 

1 

S-102-G 

Auto      fire      shutter 

3 

L-107-G 

link  ret.    screw. 

2 

S-134-E 

Film  trap  door  stud 

3 

L-114-G 

screw. 

1 

S-138-E 

Film  trap  heat  shield 

3 

L-115-G 

retaining     screw. 

1 

S-292-E 

Lateral  guide  roller 

1 

N-105-G 

shaft. 

5 

S-309-E 

Film    trap    shoes. 

2 

N-119-G 

1 

S-316-E 

Auto  fire  shutter. 

5 

S-326-E 

Film    guide    retain- 

ing   spring. 

4 

R-128-G 

2 

S-328-E 

Film  trap  door  pad 

spring. 

3 

S-142-G 

1 

S-337-E 

Lateral  guide  roller 

spring. 

2 

S-144-G 

2 

S-367-E 

Film  trap  door  hold- 

er   stud 

3 

S-145-G 

1 

T-104-E 

Film  trap. 

4 

S-150-G 

4 

A-110-G 

Framing  arm. 

3 

A-118-G 

Picture    framing 

3 

S-209-G 

handle  arm. 

3 

B-122-G 

Shutter  gear  brack- 

3 

S-222-G 

et. 

5 

C-192-G 

Intermediate     shaft 

3 

S-223-G 

retaining  collar. 

5 

C-193-G 

Spiral    driving    gear 

shaft   collar. 

4 

S-321-G 

4 

C-194-G 

Spiral    driving    gear 

3 

S-330-G 

shaft   collar. 

4 

G-lll-G 

Lower  sprocket  gear. 

1 

S-341-G 

3 

G-112-G 

Main  driving  gear. 

4 

G-115-G 

Shutter   drive   bevel 

2 

S-429-G 

4 
4 

G-116-G 
G-117-G 

gear. 
Spir.  driv.  gear  with 
broached  hole. 
Spiral   gear 

4 
4 
2 

S-443-G 
S-444-G 
S-445-G 

3 

G-133-G 

Intermediate       gear 
No.    2. 

4 

S-446-G 

3 

G-134-0 

Intermediate       gear 

2 

S-447-G 

No.    1. 

1 

W-106-G 

4 

G-135-G 

Intermediate     bevel 

gear. 

Description. 
Bevel   gear  No.   3. 
Vertical  shaft  gear. 
Bevel  gear  No.   2. 
Governor  upper  link 

holder. 

Framing  slide  lever. 
Governor  lift  lever. 
Picture  framing 

lever. 
Picture    framing 

connecting  link. 
Picture    framing 

link. 
Handle    friction 

spring'  retain  nut. 
Picture    framing 

lever   pivot   screw 

nut. 
Framing    slide    arm 

roller. 
Picture    framing 

lever  pivot  screw. 
Framing  slide  lever 

stud    set    screw. 
Framing  slide   lever 

stud  spr.   ret    scr. 
Governor    lift    lever 

pivot   screw. 
Main     driving     gear 

retaining     screw. 
Picture    framing 

link  screw. 
Picture    framing 

connecting        link' 

screw. 

Framing  slide. 
Framing  slide  lever 

spring. 
Picture    framing 

handle  frict.  spr. 
Lower    sprocket 

shaft. 

Vertical    shaft 
Intermediate  shaft. 
Upper    s  p  r  o  c  k  e  t 

shaft. 
Spiral    driving    gear 

shaft. 

Shutter  shaft 
Picture    framing 

handle        friction 

washer. 


The   Motiograph,  No.  1-A  1916  Model 

Note. — Wihile  in  general  appearance  the  mechanism  of  the 
1916  model  Motiograph  very  closely  resembles  former  mod- 
els, still  the  removal  of  the  inside  shutter  has  tended  very 


FOR    MANAGERS   AND    OPERATORS 


529 


greatly  to  simplify  the  mechanism  and  has  rendered  it  much 
easier  for  the  operator  to  assemble  and  disassemble  the  ma- 
chine. There  are  also  other  important  improvements,  as 
will  appear  further  on,  among  which  is  the  addition  of  an 
auxiliary  fly  wheel,  and  the  substitution  of  a  sliding  toggle 
joint  (the  parts  of  which  are  shown  at  A,  B,  C,  P.  5)  for  the 
ball  and  socket. 
No.  1.  Gear  Cover  M-A,  1-P,  P.  2,  carries  the  parts  shown 


Figure  261. 

attached  thereto  in  P.  2.     By  loosening  thumb   screws  233 
(two  of  them),   P.  2,  and  thumb  screw  233,  P.  4,  the  gear 
cover  may  be  pulled  away,  together  with  the  parts  attached 
thereto. 
No.  2.    The  Entire  Mechanism  may  be  swung  around  on 


530 


MOTION    PICTURE   HANDBOOK 


its  base,  in  order  to  allow  the  operator  to  get  at  the  shutter 
or  lens,  by  loosening  the  hand  wheel  underneath  the  base- 
board and  raising  pin  283^2,  P.  1. 

No.  3.    Front  Plate,  172,  P.  4,  which  carries  the  objective 
lens,  may  be  removed  by  loosening  thumbscrews  99-A  (two 


Plate  1,  Figure  262. 

of  them),  P.  4,  and  raising  the  outer  end  of  spring  275,  P.  4, 
at  the  top  edge  of  the  front  plate,  at  the  same  time  pulling 
the  top  of  the  plate  outward  and  up. 

No.  4.  The  Machine  Gate  is  opened  by  pressing  on  knob 
125-P,  P.  1.  This  knob  is  the  end  of  the  gate  latch  rod, 
which  extends  inward  and  carries  gate  latch  screw  220,  P.  1, 
as  may  be  seen  by  removing  the  front  plate  (see  Instruction 
No.  3)  and  looking  inside  the  mechanism.  Gate  latch  screw 
220,  P.  1,  is  threaded  into  this  knob  and  may  be  removed 


FOR    MANAGERS   AND    OPERATORS  531 

by  a  screwdriver.  Looking  inside  the  mechanism  you  will 
see,  in  the  upper  left  hand  corner,  a  collar  on  the  gate  latch 
rod,  held  in  place  by  a  set  screw.  This  collar  serves  to 
compress  a  small  spiral  spring.  In  order  to  remove  this 
spring,  loosen  the  set  screw  in  the  collar  and  remove  screw 
220,  P.  1,  whereupon  the  gate  latch  rod  may  be  pulled  in- 
ward, thus  releasing  both  the  collar  and  spiral  spring.  Should 
the  gate  latch  at  any  time  fail  to  work  properly,  it  is  prob- 
able that  the  head  of  gate  latch  screw  220,  P.  1,  has  become 
worn,  and  a  new  one  should  be  ordered  and  installed.  It  is 
also  possible  that  the  spring  has  become  weak,  in  which 
case  it  should  be  taken  out  and  either  stretched  until  it  gives 
sufficient  compression  or  a  new  one  may  be  installed. 

No.  5.  To  Remove  the  Machine  Gate,  unscrew  knob  127, 
P.  1,  lift  governor  rack-bar,  168,  P.  2,  off  standard  83,  P.  1,  and 
lift  the  gate  away.  In  replacing  the  gate  don't  forget  to  hook 
the  end  of  the  rack  bar  to  standard  83,  P.  1. 

Caution:  It  will  probably  never  be  necessary  to  take  the 
gate  apart,  and  if  it  is  for  any  reason  necessary  to  do  so,  I  would 
not  advise  the  operator  to  undertake  this  particular  thing 
unless  he  is  compelled  to.  When  the  gate  is  once  taken 
apart  it  is  a  somewhat  difficult  matter  to  reassemble  it  prop- 
erly, and  I  would  suggest  that  instead,  should  it  ever  be 
necessary  to  make  any  repairs  to  its  internal  mechanism, 
the  gate  be  sent  to  the  factory.  The  film  tension  bars,  96  A, 
P.  1,  and  the  tension  spring  can,  of  course,  be  removed  with- 
out taking  the  gate  apart. 

No.  6.  Aperture  Plate,  162  A,  P.  1,  may  be  removed  by 
taking  out  screws  (four  of  them)  217,  P.  1.  These  screws 
are  small,  therefore  be  careful  or  you  will  lose  them.  Better 
lay  a  piece  of  paper  underneath  to  catch  them  should  they 
fall,  or,  better  still,  handle  them  with  a  magnetized  screw- 
driver. (See  General  Instruction  No.  19.) 

No.  7.  Tension  Springs  and  Shoes. — Tension  shoes,  96  A, 
P.  1,  are  held  in  place  by  a  one-piece  square,  flat  spring,  174 
A,  P.  2,  which  may  be  seen  by  looking  into  the  gate  edge- 
wise. This  spring  not  only  holds  the  tension  shoes  in  place, 
but  also  supplies  them  with  normal  tension.  The  action  may 
be  plainly  seen  by  pressing  on  one  of  the  shoes,  at  the  same 
time  looking  into  the  gate  edgewise.  Spring  259  P,  P.  2, 
bears  on  the  lower  edge  of  spring  174  A,  P.  2,  and  by  means 
of  thumbscrew  245,  P.  2,  may  be  caused  to  supply  auxiliary 
or  increased  tension  to  the  bottom  of  the  tension  shoes. 
Tension  shoes,  96  A,  P.  1,  may  be  removed  as  follows: 


532 


MOTION    PICTURE    HANDBOOK 


Loosen  screws  294  and  222,  P.  2,  and  swing  cooling  plate  over 
to  the  left  out  of  the  way.  Next  block  fire  shutter,  163,  P.  2, 
up  out  of  the  way.  You  will  then  see  spring  174,  A,  which 
is  held  by  two  round-head  screws,  one  at  either  side  of  the 
aperture.  First,  having  backed  off  on  thumb  screw  245,  P.  2, 


233 


Plate  2,  Figure  263. 

until  spring  259,  P.  2,  is  out  of  contact  with  spring  174  A, 
remove  the  two  screws  holding  spring  174  A,  and  pressing 
in  on  the  tension  shoes  with  the  thumb  and  finger  of  one 
hand  and  in  on  the  top  and  bottom  of  spring  174  A,:  P.  2, 
with  the  thumb  and  finger  of  the  other  hand,  slip  spring 
174  A  down  slightly,  which  will  unhook  it  from  the  tension 
shoes  and  release  both  them  and  the  spring. 
In  replacing  the  shoes  and  spring,  place  the  shoes  in 


FOR    MANAGERS   AND    OPERATORS  533 

proper  position  so  that  the  hooks  on  the  lugs  will  point 
downward,  and  pressing  spring  174  A  down  flat,  slip  it  up 
under  the  hooks  until  they  are  engaged,  whereupon  replace 
the  screws  and  swing  the  cooling  plate  back  in  place,  tighten 
up  its  holding  screws  and  the  job  is  done. 

No.  8.  Automatic  Fire  Shutter  Blade,  163  P,  P.  2,  may  be 
removed  as  follows:  First  follow  Instruction  No.  5;  next 
remove  screws  219,  P.  1,  and  another  similar  screw  about 
three  inches  immediately  above.  Loosen  screw,  294,  P.  2, 
and  you  can  lift  the  entire  front  plate  of  the  gate  away,  which 
will  release  automatic  fire  shutter,  163  P,  P.  2. 

No.  9.  Tension  Spring,  259  P.  2,  may  be  removed  by  fol- 
lowing Instruction  No.  8,  and  then  taking  out  screws,  260  P, 
P.  2. 

No.  10.  Tension. — (See  General  Instruction  No.  9.)  The 
tension  may  be  increased  in  two  ways,  first  by  removing 
spring,  174  A,  P.  2  (see  Instruction  No.  7),  and  bending  it  in 
proper  direction  to  supply  added  tension,  or  by  tightening 
up  on  thumbscrew,  245  P,  P.  2.  It  is  intended  that  spring 
174  A,  P.  2,  shall  supply  proper  tension  without  help  from 
spring  259,  P.  2. 

No.  11.  To  Remove  Upper  Sprocket  Shield,  282  P,  P.  1, 
remove  screws  (two  of  them)  284  P,  P.  1. 

No.  12.  To  Remove  Upper  Sprocket,  106,  P.  4,  remove  the 
set  screw  in  the  center  of  its  hub,  and  pull  the  sprocket  off 
the  shaft.  In  replacing  it  remember  that  the  end  hav- 
ing an  offset  hub  goes  in  toward  the  casting.  If  put  on  the 
other  way  the  sprocket  will  be  out  of  line  with  the  aperture, 
and  there  will  be  trouble.  Having  removed  the  hub  you 
can  pull  its  spindle  51  A,  P.  1  and  2,  carrying  gear  87^2,  P.  2, 
out  to  the  left,  first  having  removed  the  gear  cover.  (See 
Instruction  No.  1.) 

Caution:  In  removing  upper  and  lower  sprockets  you  must 
take  the  set  screw  clear  out  before  you  can  pull  the  sprocket 
off. 

No.  13.  To  Remove  Upper  Sprocket  Idler  Bracket,  24, 
P.  4,  remove  set  screw  249,  P.  4,  loosening  screws  227  and 
265,  P.  4.  Next  remove  top  sprocket,  106,  P.  4  (see  In- 
struction No.  12),  and  you  can  pull  the  bracket  away. 

No.  UYz.  Idler  Roller,  108,  P.  4,  is  held  away  from  the 
sprocket  (see  General  Instruction  No.  12)  by  screw  241,  P.  4, 
which  is  locked  by  knurled  knob,  241,  P.  4.  Idler  roller,  108, 
may  be  removed  from  its  spindle  by  taking  out  screw  223, 
P.  1.  I  would  advise  the  operator  to  remove  the  upper,  lower 


534 


MOTION    PICTURE    HANDBOOK 


and   the   intermittent   idler  rollers   at  least   once   each  week, 
clean  and  lubricate  their  spindles,  using  a  medium  light  oil 


207  f> 

20IP 


4A 
84A 


225 


225 


18!  —  '  "%^ 


Plate  3,  Figure  264. 

for  the  purpose.     True,  there  is  an  oil  hole  in  their  center, 
but  better  take  them  off. 

No.   14.    Lower  Sprocket,   106,  P.  4,  may  be   removed  by 


FOR    MANAGERS   AND    OPERATORS  535 

taking  out  the  screw  in  its  hub  and  pulling  the  sprocket  off 
the  shaft,  first  having  raised  the  idler  bracket.  If  it  is  de- 
sired to  remove  its  spindle,  52  A,  P.  2,  which  carries  take-up 
belt  driving  pulley,  20,  P.  2,  it  will  first  be  necessary  to  fol- 
low Instruction  No.  23.  Having  done  so  you  will  see,  down 
in  a  pocket  inside  the  frame  casting,  gear  17  A,  P.  3,  which 
drives  the  lower  sprocket  shaft.  Loosen  the  set  screw  ir 
its  hub,  backing  it  off  a  considerable  distance,  as  it  is  deeply 
countersunk  into  the  shaft,  and  you  can  pull  the  driving 
pulley  and  spindle  out  to  the  left.  In  replacing  same  be 
sure  you  get  set  screw  which  holds  gear  17  A,  P.  3,  properly 
located  in  the  countersink  in  the  shaft,  and  set  it  up  tight,  be- 
cause if  this  set  screw  works  loose  it  will  be  a  job  to  get  at 
it  and  retighten. 

No.  15.  Lower  Sprocket  Idler  Bracket,  25  A,  P.  4,  may 
be  removed  by  loosening  the  screw  in  the  upper  end  of  spring 
274,  P.  4,  and  screw  249,  P.  4,  and  screw  227,  P.  4.  In  re- 
placing same  be  sure  to  tighten  up  screw  227,  P.  4,  and  the 
one  on  top  of  spring  274,  and  to  readjust  screw  249,  P.  4,  so 
that  the  spring  has  the  proper  tension.  Lower  idler  roller, 
108  A,  P.  4,  is  merely  a  guide  roller  and  sets  approximately 
one-eighth  of  an  inch  from  the  sprocket.  The  other  two 
rollers  should,  however,  be  adjusted  by  means  of  screw  241^4 
and  lock  nut  241,  P.  4,  as  per  General  Instruction  No.  12. 
Any  of  these  idler  rollers  may  be  removed  from  their  spindle 
by  taking  out  the  screw  in  the  end  thereof,  but  it  will  be 
necessary  to  take  off  the  entire  bracket  in  order  to  get  the 
center  roller  off. 

No.  16.  Gear  Bridge,  4  A,  P.  3,  may  be  removed  by  taking 
out  screws  224  A  (three  of  them),  P.  2.  Back  these  screws 
out  for  about  one-half  inch  and  then,  using  a  screwdriver, 
carefully  pry  the  bridge  away.  The  holding  screws  are 
"necked,"  in  order  that  they  may  be  left  in  the  bridge  to 
avoid  the  possibility  of  becoming  lost.  When  you  have 
backed  them  off  for  about  one-quarter  inch  they  will  release 
the  main  casting,  though  they  are  still  attached  to  the 
bridge.  In  replacing  the  bridge  be  sure  that  you  get  the 
end  of  the  spindle  carrying  gear  84,  P.  3,  properly  entered 
in  its  bearing  and  also  that  shaft  50  D,  fly  wheel  shaft  61  P, 
and  the  pin  entering  spindle  65,  all  P.  3,  are  properly  entered, 
and  that  the  locating  pins  enter  their  proper  receptacles.  Do 
not  attempt  to  drive  the  bridge  on.  If  you  start  it  right  it  will 
enter  without  any  trouble,  and  all  that  will,  in  any  event,  be 
necessary,  will  be  to  tap  the  casting  lightly  with  the  handle  of 
the  screwdriver  immediately  over  each  of  the  two  locating  pins. 


536  MOTION    PICTURE    HANDBOOK 

No.  17.  To  Remove  Revolving  Shutter  Shaft,  197  P,  P.  2, 
remove  screws  159,  P.  3,  and  158  P,  P.  4.  You  may  then 
pull  the  spindle  and  its  casting,  together  with  the  revolving 
shutter  and  gear  207  P,  P.  3,  out.  Having  done  this,  if  it  is 
desired  to  remove  the  shutter  spindle  from  the  casting,  you 
may  do  so  by  loosening  the  set  screw  in  collar,  201  P,  P.  3, 
which  will  allow  you  to  pull  the  spindle  out  of  the  casting. 

Caution:  At  either  end  of  the  shutter  spindle  bearing  is  a 
fibre  washer.  Be  sure  and  get  these  washers  back  in  place 
in  reassembling. 

No.  18.  To  Remove  Fly  Wheel  14  P,  P.  2,  follow  Instruc- 
tion No.  16,  after  which  remove  the  two  set  screws  in  the 
hub  of  the  fly  wheel.  It  is  better  to  remove  these  screws, 
as  they  are  deeply  countersunk  into  the  shaft,  then  grasping 
the  fly  wheel  on  the  other  end  of  the  shaft  to  hold  it  sta- 
tionary, twist  fly  wheel  14  P,  P.  2,  at  the  same  time  pulling 
outward,  and  thus  working  it  off  the  shaft. 

Caution:  In  replacing  be  sure  to  get  the  screws  properly 
located  in  their  countersink. 

No.  19.  To  Remove  Gear  87,  P.  2,  take  out  set  screw  129, 
P.  2,  which  releases  the  gear. 

No.  20.  To  Remove  Gear  15  A,  P.  2,  follow  Instruction 
Nos.  16  and  17,  whereupon  the  gear  may  be  pulled  off  the 
spindle. 

No.  21.  To  Remove  Crank  Shaft  50  P,  P.  3,  first  detach  the 
crank,  O-13  P,  P.  1,  then  follow  Instruction  20,  thus  releas- 
ing the  shaft,  which  may  be  pulled  out  from  the  left  hand 
or  gear  side. 

No.  22.  To  Remove  Gear  16  P,  P.  3,  follow  Instructions 
Nos.  16,  17,  18  and  20,  in  their  order,  and  then  take  out  screw 
16^  P,  P.  3.  This  releases  the  gear.  In  replacing  be  sure 
that  you  set  up  screw  16H  P,  P-  3,  tight. 

No.  23.  To  Remove  Gear  18  A,  P.  3,  follow  Instructions 
Nos.  1,  16  and  18,  and  then  remove  screw  129,  P.  3.  In  re- 
placing be  sure  to  set  screw  129  up  tight. 

No.  24.  To  Remove  Gear  17  A,  P.  3,  follow  Instructions 
Nos.  1,  16,  18  and  23,  and  then  loosen  the  set  screw  in  the 
hub  of  gear  17  A,  P.  3.  Next  loosen  the  set  screw  in  the  face 
of  belt  pulley  20,  P.  2,  and  slip  the  pulley  off  its  shaft.  You 
may  then  pull  spindle  52  A,  P.  2,  out  from  the  sprocket  side, 
thus  releasing  the  gear.. 

No.  25.  To  Remove  Automatic  Governor  Shaft  65,  P.  3, 
and  the  parts  attached  thereto,  follow  Instructions  Nos.  1,  16 


FOR    MANAGERS   AND    OPERATORS 


537 


and  18;  then,  looking  in  past  the  left-hand  edge  of  the  fly 
wheel,  you  will  see  a  set  screw  in  the  hub  of  a  casting  in 
the  end  of  standard  83,  P.  1.  Loosen  this  set  screw  until  the 
casting  will  revolve  on  the  rod,  whereupon  you  can  pull  the 
whole  governor  away.  Should  it  ever  become  necessary  to 
renew  the  springs,  gear,  or  other  parts  of  the  governor,  I 
would  advise  that  it  be  sent  to  the  factory  by  insured  parcel 


106 


Plate  4,  Figure  265. 

post.  Don't  try  to  do  this  particular  job  yourself.  In  replacing 
the  governor  the  set  screw  in  the  casting  is  countersunk 
deeply  into  the  shaft,  and  it  is  necessary  that  this  screw 
enter  the  countersink,  else  standard  83,  P.  1,  will  not  set 
right,  and  your  automatic  fire  shutter  will  not  work. 

No.  26.    Framing  Carriage  D-l,  P.  4,  carrying  outside  fly 


538  MOTION    PICTURE    HANDBOOK 

wheel,  D-38,  P.  1,  may  be  removed  as  follows:  First  loosen 
screws  216  (two  of  them),  P.  4,  and  then,  by  means  of 
knurled  knob  at  its  top,  unscrew  framing  carriage  guide  rod 
72  P,  P.  4,  and  pull  it  out.  Next  remove  the  screw  which 
holds  the  upper  end  of  the  link  which  joins  the  framing  car- 
riage and  framing  lever  casting  11  P,  P.  4.  Next  loosen  the 
two  screws,  one  at  each  lower  corner  of  the  nickel  plated 
shield  in  the  side  of  the  mechanism  back  of  the  fly  wheel, 
and  raise  knob  296,  P.  1.  You  may  then,  by  working  it 
around  a  little,  pull  the  whole  framing  carriage  out  to  the 
right — on  the  crank  side  of  the  mechanism. 

No.  27.  To  Remove  Fly  Wheel  Shaft  61  P,  P.  3,  follow 
Instructions  Nos.  1,  16,  18  and  26,  then  loosen  a  set  screw 
in  the  face  of  the  framing  casting  just  behind  the  lower  gate 
hinge.  You  will  be  obliged  to  remove  the  gate  in  order  to 
get-  at  this  set  screw.  (See  Instruction  No.  5.)  This  set 
screw  holds  the  bronze  bearing  in  which  the  shaft  runs,  and 
you  may  then,  using  either  a  copper  or  a  hard  wood  punch, 
drive  the  shaft  bearing  and  inner  end  of  the  toggle  out  into 
the  interior  of  the  frame  casting. 

No.  28.  Striper  Plate  D-32,  P.  1,  (F-F,  P.  5),  may  be  re- 
moved by  taking  out  the  three  screws  at  its  lower  end.  See 
P.  5.) 

No.  29.  Fly  Wheel,  D-38,  P.  1,  may  be  removed  by  taking 
out  the  two  set  screws  in  its  hub.  They  are  deeply  counter- 
sunk, and  must  be  backed  out  for  quite  a  distance  before 
the  wheel  will  be  released.  When  the  wheel  is  released  from 
the  screws,  hold  the  fly  wheel  on  the  opposite  end  stationary 
while  you  pull  the  wheel  off  with  a  twisting  motion. 

No.  30.  To  Open  the  Oil  Well  follow  Instruction  No.  29, 
and  then  loosen  the  screw  at  each  lower  corner  of  the  nickel 
plated  shield  behind  the  fly  wheel  and  remove  it;  next  re- 
move four  machine  screws  in  the  black  casting  on  the  end  of 
the  framing  carriage.  These  screws  hold  the  cover  of  well 
E,  P.  5,  and  having  removed  them  you  can  pull  the  cover  off, 
tapping  it  lightly  to  break  the  joint.  Before  starting  this  job, 
you  can,  if  you  wish,  remove  the  whole  framing  carriage  from 
the  machine.  See  Instruction  No.  26.  It  is  well  to  remove 
the  oil  well  cover,  say  once  in  each  five  or  six  hundred  hours 
running,  and  clean  it  out  thoroughly. 

Never  use  graphite  in  the  oil  well  unless  you  want  trouble, 
and  plenty  of  it. 

Caution:  In  replacing  the  oil  well  cover  be  sure  that  you 
wipe  both  the  surfaces  perfectly  clean.  If  you  do  not  there 
is  apt  to  be  a  leakage  of  oil. 


FOR    MANAGERS   AND    OPERATORS 


539 


Note. — Directions  follow  for  the  removal  and  renewal  of 
cam,  star  and  intermittent  sprocket  and  their  bushings.  I 
do  not,  however,  advise  this.  It  is  much  better  to  purchase 
an  extra  framing  carriage,  and  when  anything  goes  wrong 
with  the  old  one,  or  when  excessive  wear  develops  in  the 
bushings,  spindles,  intermittent  sprocket,  or  other  parts,  in- 
sert the  new  carriage  in  the  machine  and  send  the  old  one 
to  the  factory  by  parcel  post  for  repairs.  It  is,  of  course, 
possible  that  the  operator  can  and  will  make  the  necessary 


Plate  5,  Figure  266. 

repairs  in  an  entirely  satisfactory  manner.  Still,  when  one 
considers  the  delicacy  of  the  parts  and  the  fine  adjustment 
necessary,  one  readily  sees  that  this  can  be  best  done  at  the 
factory,  where  all  necessary  tools  and  men  skilled  in  this 
class  of  work  are  available. 

No.  31.  Cam  Shaft  X,  P.  5,  carrying  cam  G,  P.  5,  may  be 
removed  by  following  Instruction  No.  30,  and  then  loosening 
the  set  screws  D-13  (two  of  them)  in  part  D-12,  P.  4.  Back 
these  screws  out  a  considerable  distance,  as  they  are  deeply 
countersunk  in  to  the  shaft.  Having  done  so  you  can  pull 
the  cam  and  shaft  away,  which  releases  part  D-12,  P.  4. 


540  MOTION    PICTURE    HANDBOOK 

No.  32.  The  Star  and  its  Shaft  J,  P.  5,  may  be  removed 
by  following  Instructions  Nos.  26,  28,  and  31.  Having  done  so, 
take  out  the  two  set  screws  in  the  hub  of  intermittent 
sprocket  D^IO,  P.  1,  and  you  can  pull  the  star  and  shaft  out. 

No.  33.  To  Remove  the  Bearings  of  the  Intermittent 
sprocket  Shaft  follow  Instruction  No.  32.  The  bearing  on  the 
star  end  is  held  by  a  set  screw,  the  head  of  which  is  in  the 
top  of  the  casting,  and  the  bearing  in  the  other  end  is  held 
by  a  set  screw  in  the  face  of  the  casting  at  the  end  of  the 
bearing.  Remove  these  screws  and  you  can  drive  the  bear- 
ing out  and  insert  new  ones.  The  screws  in  the  face  of  the 
casting  which  holds  the  left  hand  bearing  should  be  set  up 
just  far  enough  so  there  is  no  end  motion  in  the  intermittent 
sprocket.  If  you  set  it  tight  you  will  bind  the  sprocket;  if  you 
leave  it  too  loose  the  sprocket  is  apt  to  have  end  play- 
No.  34.  The  Bearings  of  the  Cam  Shaft  may  be  removed 
by  following  Instructions  No.  26  and  31.  This  bearing  ex- 
tends the  full  length  of  the  casting.  It  is  held  at  one  end  by 
a  set  screw,  the  head  of  which  is  in  the  top  of  the  framing 
carriage  casting;  the  other  end  is  held  by .  two  set  screws 
which  bear  against  the  lug  in  the  end  of  the  bearing.  This 
bearing  is  eccentric.  Having  loosened  the  two  set  screws 
which  bear  against  the  lug,  and  the  one  in  the  top  of  the 
casting  which  holds  its  other  end,  you  may  drive  the  bearing 
out,  using  a  hard  wood  punch.  In  replacing  it  it  will  be 
necessary  to  adjust  the  bearing  carefully.  Proceed  under  In- 
struction No.  35. 

No.  35.  Adjusting  Intermittent  Movement. — When  the  in- 
termittent sprocket  develops  considerable  circumferential  play, 
or  the  intermittent  movement  becomes  noisy  it  is  in  need 
of  adjustment.  Proceed  as  follows.  Set  screws  D-26,  P.  4,  (two 
of  them),  bear  against  eccentric  bearing  lug  D-5,  P.  4,  and  a 
movement  of  these  set  screws  has  the  effect  of  altering 
relation  of  the  star  and  cam  to  each  other.  When  you  loosen 
the  lower  screw  and  tighten  down  on  the  upper  one  you 
tighten  the  cam  against  the  star,  thus  eliminating  the  lost 
motion  in  the  intermittent  sprocket,  but  you  must  be  very 
careful  and  not  get  the  movement  too  tight  or  you  will  have 
trouble,  particularly  if  the  adjustment  be  done  while  the 
machine  is  cold.  Tighten  up  on  the  upper  screw,  first  having 
backed  off  on  the  lower  one,  until  you  can  feel  just  the 
least  bit  of  shake  in  the  intermittent  sprocket  when  you  try  it 
with  your  finger.  Having  got  your  adjustment  made  tighten 
up  both  set  screws.  This  adjustment  must  be  made  with  the 


FOR    MANAGERS   AND    OPERATORS  541 

movement  "on  the  lock" — in  position  when  the  sprocket  is 
locked. 

No.  36.  Adjusting  the  Framing  Carriage. — The  ease  with 
which  the  framing  carriage  moves  up  and  down  is  governed 
by  screws  216  (two  of  them),  P.  4.  Tightening  these  screws 
has  the  effect  of  pressing  together  the  casting  lug  on  the 
guide  rod,  thus  making  the  carriage  move  harder;  conversely 
loosening  these  screws  makes  it  move  more  easily. 

No.  37.  Bearings. — All  bearings  of  the  Motiograph  ma- 
chine are  held  by  set  screws,  and  may  easily  be  removed  for 
replacement.  Bearing  194,  P.  4,  is  held  by  set  screw  235,  P.  4. 
The  bearing  which  can  be  seen  just  at  the  bottom  of  gear 
207-P,  P.'  3,  is  held  by  set  screw  103-A,  P..  4.  The  bearings 
in  bridge  4-A,  P.  3,  are  held  by  set  screws  225  (three  of 
them),  P.  3. 

No.  38.  Oil.— Never  under  any  circumstances  use  graphite  in 
the  oil  well.  Graphite  is  ordinarily  one  of  the  finest  lubricants 
made,  but  it  does  not  work  at  all  satisfactorily  in  the  inter- 
mittent movement  of  a  projection  machine,  nor  do  I  advise 
its  use  on  gears  or  on  any  part  of  the  mechanism.  I  would 
advise  the  use  of  a  very  heavy  oil,  such  as  Mobile  B,  which 
can  be  had  at  almost  any  garage,  for  the  toggle  joint.  This 
joint  works,  under  considerable  pressure,  at  high  speed.  If 
a  light  oil  be  used  it  is  likely  to  be  thrown  off  rapidly.  Mo- 
bile B  ought  to  be  about  right. 

No.  39.  i  Lining  the  Sprockets. — See  General  Instruction 
No.  4. 

No.  40.  Keeping  the  Sprockets  Clean.— See  General  In- 
struction No.  3. 

No.  41.  Setting  the  Shutter.— See  General  Instruction  No. 
18.  , 

No.  42.  Sprocket  Teeth. — See  General  Instruction  No.  8. 
No.  43.  Motiograph  Take-up  uses  a  flat  belt  about  one- 
half  inch  wide.  This  belt  is  driven  by  pulley  20,  P.  2,  the 
driven  .pulley  being  shown,  not  attached  to  the  machine, 
at  10  A,  P.  1.  The  belt  is  given  the  necessary  tension  by 
idler  pulley  109,  P.  1,  the  tension  being  governed  by  set  screw 
156,  P.  1.  This  plan  is  quite  efficient,  but  the  operator  should 
see  to  it  that  the  adjustment  of  idler  109,  P.  1,  is  carefully 
made,  else  there  will  be  a  heavy  pull  on  the  film,  which  is,  of 
course,  injurious. 


542 


MOTION    PICTURE    HANDBOOK 


PARTS  FOR   MECHANISM  OF  NO.  1-A  MOTIOGRAPH 
MODEL  1916 

Note:  In  ordering  parts  give  serial  number  of  mechanism 
and  article  number.  That  is  all  that  is  necessary. 

Numbers  in  first  column  indicate  plate  in  which  the  part 
is  shown. 


Plate  Article 

Plate  Article 

No.        No. 

No.        No. 

1—     1-P 

Main  frame  casting: 

4  —  25-A 

Roller    bracket. 

of    mechanism. 

lower,  with  shafts. 

—  •     3-P 
3  —     4-  A 
—     7-A 

Gear  cover. 
Gear  bridge. 
Upper      reel      arm, 

4—  25% 

1  —  25% 

Screw  to  bind  roller 
brackets  on  shafts. 
Screw  to  bind  front 

1—     9-P 

casting    only. 
Lower     reel      arm, 

eccentric  roller 
shaft      in      lower 

casting  only. 

bracket. 

1_  IO-A 
4—  11-P 

Take-up    belt    ten- 
sion idler  bracket. 
Framing  lever  cast- 
ing. 

—  29 

—  26y2 

Magazine    latch, 
large  piece. 
Spring    for    maga- 

— 12-A 

Hand  bolt  to  clamp 
mec'hanism          to 

—  30 

zine  latch. 
Magazine    latch. 

baso. 

small  piece. 

—  13-P 

Crank  handle  cast- 

— 31 

Hinge  on  magazine 

ing,  only. 

body. 

1—  013-P 

Crank  handle  com- 

— 32 

Hinge  on  magazine 

plete. 

cover. 

2_  14-P 

Balance    wheel. 

—  32% 

Spring    for    maga- 

3— 15-A 

Main  gear. 

zine  hinge. 

3—  16-P 

Double      gear     be- 

— 33-A 

Fire    trap,     casting 

tween    main    gear 

only. 

and  balance  shaft 

—  33-CT 

Fire  trap  complete, 

gear. 

with  rollers. 

3_  16%-P 

Screw     for     double 

—  F33% 

Spider  casting  only, 

gear  No.   16-P. 

for    lower    maga- 

3 —  17-A 

Gear        on        lower 

zine. 

sprocket  shaft. 

—  37-P 

Stereo      lens      arm 

3—  18-A 

Gear   between    bal- 

bracket. 

ance     shaft    gear 

—  38-A 

Shutter    shaft    and 

and  lower  sprock- 

gear,   solid. 

et  shaft  gear. 

—  39-A 

Shutter    shaft    and 

—  19 

Governor  crank, 

gear,  main,  hollow. 

complete. 

—  41-A 

Shutter  drive  shaft 

2  —  20 

Small    belt    pulley 

screw. 

and  screw. 

—  42-A 

Bushing  for  govern- 

1— 21 

Large    belt     pulley 

or  drive  shaft. 

and  screw. 

—  44-A 

Screw   for   gear   on 

—  22-P 

Stereo    lens    mount 

upper    sprocket 

ring. 

shaft. 

—  22%-P 

Stereo   lens   retain- 

— 45-A 

Bevel  gear  on  shut- 

ing ring. 

ter  drive  shaft. 

—  22% 

Thumb     screw    for 

—  461-A 

\Bevel  gear  on  shut- 

stereo lens  mount 

ter    shaft. 

ring. 

—  47-A 

Intermediate    gears 

—  23%-P 

Stereo      lens      ring 

in     shutter     gear 

complete,  less  lens. 

case. 

4—  24 

Roller  bracket,  up- 

— 48-A 

Screws    for    clamp- 

per,   with    shaft. 

ing   inner   shutter 

4  -  24% 

Screw        to        bind 

wing  on  gear  hub. 

roller      shaft      in 

3—  50-P 

Crank     shaft     with 

upper  bracket. 

pin. 

FOR    MANAGERS   AND    OPERATORS 


543 


Plate  Article 
No.         No. 
1—  51-A 

3—  52-A 

—  59-A 

—  60-A 
3—  61-P 

—  63-A 

—  64-A 

—  65 

3—  65-GC 

—  60-A 

4—  71-P 
4—  72-P 


4—  74 

2—  75-P 

—  76 

—  80-A 

1—  81 
1—  82 

1 —  82% 

1—  83 

3 —  84-A 

2—  87 

2—  87% 

3—  90 

—  91 

—  91%-M 

—  92-A 

—  93-A 

1 — 96-A 
2—  97-A 

4—  99-A 
— 103-A 


Upper   sprocket 

shaft. 
Lower  sprocket 

shaft. 

Upper  reel  shaft. 
Lower  reel  shaft. 
Balance  shaft  and 

pinion,   one  piece. 
Upper    fire    shield. 
Lower    fire    shield. 
Governor    shaft. 
Governor  complete. 
Bushing    for    shut- 
ter drive   shaft. 
Framing:    device 

guide  rod. 
Framing    device 

slide     rod,      long, 

with  head. 
Framing  lever  con- 
necting screw. 
Framing       lever 

handle. 
Screw        to        hold 

framing    lever    in 

frame. 

Bushing    for    shut- 
ter      gear       case 

(rear). 
Shaft      for      roller 

brackets. 
Roller    arbors     for 

top       or      bottom 

roller  bracket. 
Eccentric    roller 

arbor     for     lower 

roller  bracket. 
Governor      crank 

shaft. 
Gear     on     governor 

drive  shaft. 
Gear        on       upper 

sprocket  shaft. 
Intermediate    gear, 

email. 
Gear    on     governor 

shaft    and   hub. 
Stereopticon      slide 

rod    to    hold    lens 

ring. 
Wing        nut        and 

washer  for  No.  91. 
Screw       to       locate 

shutter  gear  case. 
Screw       to       retain 

shutter  gear  case 

in   frame. 
Film    tension    shoes, 

each. 
Round  aperture 

heat    arrester    on 

film  gate. 
Thumb     screw     for 

front  plate   (2). 
Screw       to       clamp 

shutter  drive  bush- 
ing. 


Plate  Article 

No.        No. 

1  —  105-A 

Cap  for  hole,  when 

changing  over  '09 

screw   for   clamp- 

ing mechanism  to 

base. 

4—106 

Sprocket,   upper  or 

lower. 

1—108 

Idler    rolls,     hard- 

ened steel. 

4—  108-A 

Idler       film       roll. 

hardened,       lower 

roller  bracket. 

1—109 

Tension   pulley  for 

take-up   belt. 

3—110 

Roller      guide      on 

governor  shaft. 

3—111 

Governor     balls, 

brass   (two). 

—  114-A 

Shutter  gear  casing 

complete      with 

gears. 

1—116 

Roller,        complete 

for    top    of    gate, 

with      shaft     and 

spring. 

1  —  116-A 

Roller,  top  of  gate, 

solid    end.    hard- 

ened. 

1—116% 

Spring      for      gate 

roller. 

1—11  6%  -A 

Roller,  top  of  gate, 

spring   end  hard- 

ened. 

—  118-A 

Spring  for  plunger, 

to  locate  mechan- 

ism on  base. 

—  119 

Center  pin  in  hing« 

of   magazine. 

1—  120-P 

Side  plate. 

—  121 

Nut,       upper      reel 

shaft. 

—123 

Collar  on  gate  latch 

rod. 

1—  125-P 

Gate  latch   rod. 

1  —  126 

Shaft  for  No.  116. 

1—127 

Ball  screw  for  gate 

hinge. 

—128 

Screws     to     fasten 

upper     or     lower 

reel  arm  to  frame. 

3—129 

Shaft  screw,   hard- 

ened, for   gear  or 

for     belt     tension 

pulley     or     stereo 

lens  bracket. 

—  133 

Pin      in      governor 

shaft. 

—135 

Pin     for     governor 

drive    gear. 

3  —  146-P 

Front       shutter 

bracket  casting. 

—  148 

Pin      in     gear     on 

governor  shaft. 

1—154 

Screw      to      fasten 

crank   to  shaft. 

1—155 

Screw        to        hold 

wood    handle    on 

stud. 

544 


MOTION    PICTURE    HANDBOOK 


Plate  Article 

Plate  Article 

No.        No. 

No.        No. 

1—156 

Adjusting    screw 

—  202 

for    take-up    belt 

tension  pulley. 

1  —  157  . 

Lock  nut  for  screw 

—  204 

No.    156. 

4—  15&-P 

Front       shutter 

2—205 

bracket      casting, 

top    screw. 

—  206-A 

4—  159-P 

Front       shutter 

bracket      casting, 

3—  20-/-P 

lower  screw. 

1—  160-P 

Main  frame  of  film 

4  —  208 

-—  161-P 

gate. 
Front       shutter 

—209 

complete,      t  w  o  - 

wing. 

1—  162-A 

Aperture    plate. 

2—212. 

2—  163-P 

Automatic          fi  r  e 

shutter  and  gear. 

2—  164-P 

Heat       shield       on 

1—217  . 

4—  167-A 

gate. 
Link      to      connect 

—218 

framing  device. 

with    No.    11-A. 

1  —  219  , 

2—168 

Rack    bar    for    fire 

shutter. 

1—220 

—169 

Governor    strips. 

—  170-A 

Shutter  wing   (out- 

— 221 

-t       \ 

er)      with      collet 

and  screws. 

2  —  222 

—  171-A 

Shutter    wing     (in- 

ner). 

4—172 

Front   plate. 

—  F-173" 

Stud    in    crank    for 

1—223 

wood  handle. 

2—  174-A 

Film  tension  spring 

2—  224-A 

to  hold  No.   96-A. 

3—175 

Governor  spring. 

—  176-P 

Front  shutter  com- 

2 —  225 

plete,   three-wing. 

—  178-P 

Front  shutter  blade 

4—227 

only. 

—  179-P 

Hub       plates       for 

front  shutter   (2). 

230-P 

—  180-P  '." 

Hub        for        front 

3—181 

shutter. 
Small     bushing     in 

1—231 

gear     bridge     for 
balance     wheel 

4—232 

—  182-P 

shaft. 
Large   bushing    for 

2—233 

* 

balance  arbor. 

2—  193-A 

Bushing    in    bridge 

4'—  235    ? 

for  governor  shaft. 

4  —  194 

Bushing    in    frame 

for  governor  shaft. 

—  237-P' 

—  195-P 

Screw      for      front 

shutter. 

—  196-P 

Rivets      for      front 

—  238-P 

shutter. 

2—  197-P 

Front  shutter  shaft. 

4  —  241 

2—  198-P 

Front  shutter  shaft 

with  gear. 

2—  199-P 

•   Collar      for      front 

4  —  241% 

shutter  shaft. 

—200 

Screw    in    governor 

crank. 

4—241% 

3—  201-P 

Collar      screw      for 

front  shutter  shaft. 

Locating  screw  for 
idler  bracket 
spring. 

Screw    for    sprock- 
ets, upperor  lower. 
.   Screw    for    balance 
wheel. 

Screw  for  shutter 
wing  collet. 

Spiral       gear       for 
front  shutter  shaft. 
Locating  screw  for 
front    plate. 

Screw  to  fasten 
magazines  to  spi- 
ders. 

Screw  to  fasten 
heat  shield  to 
gate. 

Screw  for  aperture 
plate. 

Screw  for  lower 
fire  shield. 

Screw  for  studs 
on  gate. 

Screw  for  gate 
latch. 

Screw  for  film  ten- 
sion spring. 

Screw        to        hold 
round    aperture 
heat     arrester     to 
'     No.    164-A. 

Screw  to  hold  idler 
roller  on  shafts. 

Screw  to  hold 
bridge  on  main 
frame. 

Screw  to  hold  bush- 
ings in  bridge. 

Locating  screw, 
for  roller  brack- 
ets. 

Spiral  gear  for  shut- 
ter drive  shaft. 

Screw  for  gear 
cover,  upper. 

Screw  for  gear 
cover,  rear. 

Screw  for  gear 
cover,  front. 

Screw  to  clamp 
governor  bushing 
in  frame. 

Screw  for  attach- 
ing magazine  to 
reel  arm. 

Magazine  body  and 
cover. 

Lock  nut  on  roller 
bracket  adjusting 
screw. 

Adjusting  screw, 
upper  rollerbrack- 
et. 

Adjusting  screw, 
lower  rollerbrack- 
et. 


FOR    MANAGERS   AND    OPERATORS 


545 


Plat*  Article 

Plate  Article 

No.        No. 

No.        No. 

2—  242-P 

Fibre    washers    for 

1  —  283% 

Locating       plunger 

front      shutter 

head. 

shaft. 

—  287-P 

Shutter  drive  shaft 

—  243-P 

Collar     for     crank 

with    gear    230-P 

shaft. 

and   gear   281-P 

—244 

Screw   for  locating 

—288 

Shutter  gear  case 

crank  handle. 

—  289 

Screws     to     clamp 

2—  245-P 

Adjustable    tension 

bushing  in  shutter 

thumb  screw. 

gear  case. 

—  247-P 

Adjustable    tension 

—  290 

Shaft  for  interme- 

stud  on   heat   ar- 

diate     gears       in 

rester. 

shutter  gear  case. 

4  —  249 

Screw  to  hold  roll- 

—291 

Screw    in    gear    on 

er  bracket  in  place. 

lower    sprocket 

—  251-A 

Roller     for     maga- 

shaft.. 

zine    fire    trap. 

2—294 

Screw  for  upper  fire 

—  253-A 

Shaft    for    roll     in 

shield. 

magazine  fire  trap. 

2—294% 

Screw  for  heat  ar- 

—255 

Screw  to  hold  traps 

rester  gate. 

to    magazines. 

1—  295-P 

Latch  pin  for   side 

—257 

Screw    for    nut    on 

plate. 

reel    shaft. 

1—296 

Nut  for  latch  pin. 

—  258%-P 

Spring      for      gate 

—297 

Spring  for  latch  pin. 

latch   rod. 

—  298-P 

Screw      for      side 

2—  259-P 

Adjustable    tension 

plate,      same      as 

spring. 

No.    48-A. 

2—  260-P 

Adjustable    tension 

—299 

Bushing   for    shut- 

spring screw,  same 

ter       gear       case 

as       door       latch 

(front). 

collar   screw. 

4—  D   1 

Horizontal     main 

1—261 

Wood     handle     for 

casting. 

crank. 

4—  D    2 

Vertical        casting, 

—263 

Screw      for      small 

cap    for    D-l. 

belt  pulley. 

—  D   3 

Large    bushing    for 

4  —  265 

Screw      for      roller 

geneva  star  shaft. 

bracket    springs. 

—  D   4 

Small    bushing    for 

—  267-P 

Screw      to       locate 

geneva  star  shaft. 

framer  guide  rod. 

4—  D   5 

Eccentric     bushing 

—268 

Button  in  magazine 

for     geneva     cam 

latch   screw. 

shaft. 

—269 

Screw     for     maga- 

— D   6 

Geneva      cam     and 

zine  latch. 

shaft. 

—  271-P 

Taper   pin  for  disc 

—  D   7 

Geneva    driver    pin 

on  balance  arbor. 

(hardened). 

4—  270-P 

Disc      on      balance 

—  D   9 

Geneva      star     and 

arbor. 

shaft  (one  piece). 

4—274 

Spring     for     upper 

1—  D10 

Intermittent  sprock- 

and   lower    roller 

et   ('hardened). 

bracket  (3  pieces). 

-^Dll 

Screws  for  sprock- 

4 —  275 

Spring  to  hold  front 

et  (hardened)  (2). 

plate  (2  pieces). 

4—  D12 

Disc  on  cam  shaft. 

—  276-P 

Set   screw    to   fast- 

4 —  D13 

Screw       to      fasten 

en    large    balance 

D-12      to     geneva 

shaft    bushing    in 

cam  shaft   (hard- 

main frame. 

ened). 

—  277-A 

Take-up    belt. 

1  —  D14 

Intermittent      idler 

4—278 

Screw   for  No.    275 

roller  bracket  and 

springs,       front 

shaft. 

plate. 

—  D15 

Idler    roller,     same 

4—  279-P 

Disc       between 

as  No.   108. 

framer    and    bal- 

—D16 

Pin    to    hold    D-14 

ance  arbor. 

to  D-l. 

—  281-P 

Gear      on      shutter 

1—  D17 

Springs       to       hold 

drive  shaft. 

D-14     in     position 

1  —  282-P 

Guard     for      upper 

(hardened). 

sprocket. 

1—  D18 

Screw  to  hold  D-17 

1—283 

Plunger    to    locate 

to  D-l. 

mechanism         o  n 

—  D19 

Adjusting  screw  for 

base. 

D-14. 

1  —  28  4  -P 

Screw     for     upper 

—  D20 

Screw      to      clamp 

sprocket  guard. 

D-19. 

546 


MOTION    PICTURE    HANDBOOK 


Plate  Article 
No.        No. 
— D21 


—  D22 

—  .D23 

—  D24 

—  D25 
4  —  D26 

—  D27 

—  D28 

4—  D29 

4—  D30 

—  D31 

1—  D32 

—  D33 

—  D34 

—  D35 

—  D36 

—  D37 
1  —  D38 


—  D40 


Screw  to  clamp 
roller  shaft  in  in- 
termittent brack- 
et. 

Screw  to  hold  D-15 
on  shaft,  same  as 
No.  223. 

Screw  to  clamp 
D-3  in  Dl. 

Screw  to  clamp 
D-4  in  D-l. 

Screw  to  clamp 
D-5  in  D-l. 

Adjusting  screw  for 
D-5  (2). 

Screw  to  fasten 
D-2  to  D-l. 

Take-up  screw  to 
adjust  framer  on 
guide  rod. 

Screws  in  D-2  to 
adjust  friction  on 
slide  rod  (2). 

Oil   cup  on  D-2. 

Pin  in  D-2  for  con- 
necting link. 

Stripper  plate. 

Stripper  plate 
screws. 

Dowel  pins  for  D-2. 

Screw  to  hold  D-4 
in  place. 

Bushing  for  framer 
cap  No.  02. 

Screw  for  bushing 
on  D-36. 

Balance  wheel  on 
cam  shaft. 

Balance  wheel 
screw,  same  as 
No.  249. 

Intermittent  roller 
arbor. 


Plate  Article 
No.        No. 
2— MA  1-P 
2— MA  2-P 

2— MA  3-P 
2— MA  4 

2 — MA  5 
2 — MA  6 
2 — MA  7 


2— MA  8 
2 — MA  9 


2— MA11 
2 — MAI  2 

2— MAI  3 

— MAI  4 
—MAI  6 

— <MA17 
— MAI  9 

— MA20 
— MA21 


Gear    cover. 

Support  casting  for 
idler  pulley  arm. 

Idler   pulley   arm. 

Large  belt  pulley 
and  screw. 

Socket  shaft  for 
large  belt  pulley. 

Bushing  for  large 
belt  pulley  shaft. 

Small  belt  pulley 
and  screw  for 
motor  shaft. 

Idler    pulley. 

Screws  to  fasten 
support  casting  to 
gear  cover  (3). 

Retaining  screw  for 
idler  pulley  arm. 

Adjusting  screw  for 
idler  pulley  arm. 

Locking  nuts  for 
adjusting  screw 
MA-11  (2). 

Screw  for  idler 
pulley,  hardened. 

Belt  for  motor. 

Motor  pulley  at- 
tachment com- 
plete. 

Plate  casting  to 
attach  motor  to 
swivel  casting  on 
pedestal. 

Screws  to  fasten 
MA17  to  swivel 
casting  on  ped- 
estal. 

Screws  to  fasten 
motor  to  plate  (4). 

Nuts  for  screw* 
MA20  (4). 


The  Baird  Machine  . 

THE  mechanism  of  the  Baird  machine  is  completely 
inclosed  in  a  casing  composed  of  three  castings  of 
aluminum.  These  consist  of  a  front  plate,  a  door  on 
the  operator's  side  and  a  door  on  the  gear  side.  In  addition 
to  this  is  the  gate,  which  is  of  cast  iron.  In  the  various  cuts 
the  casing  with  the  exception  of  the  gate  has  been  removed  in 
order  to  show  the  mechanism  more  completely. 

Instruction  No.  1. — To  remove  revolving  shutter  310P,  P.  2, 
complete  with  its  housing  and  lens  tube  318P,  P.  3,  proceed 
as  follows:  Loosen  screw  867P,  P.  1,  and  pull  the  entire 
shutter,  including  its  casing,  straight  out  away  from  the  ma- 
chine. Shaft  312P,  P.  2,  which  is  hexagonal  in  shape,  is  not 
attached  rigidly  to  the  mechanism,  but  telescopes  into  the 
hexagonal  hole  in  shaft  130P,  P.  3. 

No.  2v — In  order  to  remove  the  casing  of  the  machine,  first 


FOR    MANAGERS    AND    OPERATORS 


547 


follow   instruction    No.    1,    and    then    remove    seven    screws 
which  secure  the  front  casing  to  mechanism.     This  releases 


<7Ke  EU-d  Motion   Pictu 
Vie*'  of  operatiup  -ikl 

/iota.-  OOachine  will  tilt  17 
this  and  £.5°  tha.  front  lags  must  be  sawed 


Figure  267. 

the  entire  casing  from  the  mechanism,  including  two  doors 
but  not  including  the  gate. 


548  MOTION    PICTURE    HANDBOOK 

No.  3. — To  remove  the  cover  for  the  shutter  casing  (not 
shown  in  the  cut)  grasp  the  cover  and  turn  one-quarter  inch 
to  the  left.  It  will  then  be  disengaged  and  can  be  pulled  off. 

No.  4. — In  order  to  remove  shutter  310P,  P.  2,  drive  out 
the  taper  pin  in  the  hub  and  pull  it  off  the  shaft. 

No.  5. — To  remove  shutter  shaft  312P,  P.  2  and  3,  follow 
instructions  Nos.  3  and  4,  which  will  disclose  a  steel  ring 
containing  in  its  face  three  machine  screws.  Take  out  these 
screws  and  pull  the  ring  off,  which  will  release  shutter  shaft 
312P,  P.  2  and  3,  and  its  ball  bearing.  Should  it  become 
necessary  at  any  time  to  replace  this  ball  bearing,  you  must 
order  the  shaft  and  bearing  complete  from  the  manufacturer, 
as  the  bearing  is  placed  on  the  shaft  under  heavy  pressure. 
The  stock  number  of  this  shaft  is  312P  and  of  the  ball  bear- 
ing 320P.  The  replacing  of  this  shaft  is  merely  a  reversion 
of  the  process  of  its  removal,  but  in  replacing  the  steel  ring 
(stock  number  319P)  be  sure  the  ball  bearing  is  properly 
centered  before  tightening  down  the  three  holding  screws, 
else  there  may  be  vibration.  The  best  way  to  accomplish  the 
centering  is  to  put  in  the  three  holding  screws,  tighten  them 
up  and  then  back  them  off  about  one  full  turn.  Now  start 
the  motor,  and  while  the  machine  is  running,  grasp  the  steel 
holding  ring  between  your  thumb  and  finger,  and  you  can 
tell  by  the  sense  of  touch  when  it  is  properly  centered; 
whereupon  tighten  up  the  three  holding  screws  tight. 

No.  6. — The  governor,  the  weight  and  parts  of  which  are 
shown  at  145P,  P.  2,  is  >held  by  two  ball  bearings  clamped  in 
the  holding  casting  by  screws  853P,  P.  2.  The  entire  gover- 
nor, including  the  ball  bearings,  may  be  removed  as  a  unit 
by  following  instructions  Nos.  1  and  2.  Then  remove  taper 
pin  70P,  P.  2,  and  pull  off  arm  117P,  P.  2.  Next  remove  screw 
141P,  P.  2,  and  a  similar  screw  immediately  under  the  arrow 
head  of  853P,  P.  2;  this  releases  bar  140P,  P.  2.  Next  loosen 
screws  853P,  P.  2,  whereupon  the  entire  governor  including 
the  ball  races  and  beveled  gear  may  be  pulled  out  toward  the 
front. 

No.  7.— To  remove  ball  bearing  138P,  P.  3,  and  spring  134P, 

P.  2,  follow  instructions  Nos.  1,  2  and  6,  which  releases  the 
governor  as  a  unit.  Now  remove  screw  822P,  P.  2,  and  its 
mate  on  the  opposite  side  and  tap  lightly  on  the  end  of  shaft 
130P,  P.  3.  The  ball  bearing  is  just  a  tight  fit,  and  by  tap- 
ping lightly  on  the  end  of  the  shaft  with  a  copper  or  brass 
punch  it  will  slip  off  the  shaft,  and  this  releases  the  governor, 
weight,  spring  and  sleeve. 


FOR    MANAGERS   AND    OPERATORS 


549 


No.  8. — To  remove  spring  134P,  P.  2,  follow  instruction 
No.  7. 

No.  9. — To  remove  weight  145 P,  P.  2,  follow  instruction 
No.  7,  and  then  drive  out  the  pins  holding  the  governor- 


Plate  1,  Figure  268. 

carrying  arms.     These   pins   are   not   tapered    and    may   be 
driven  either  way. 

No.  10. — To  remove  ball  race  on  inner  end  of  governor 
shaft,  follow  instruction  No.  7,  and  then  drive  out  taper  pin 
in  hub  of  gear  136P,  P.  2.  The  large  end  of  each  taper  pin 
used  in  this  machine  may  be  recognized  by  a  file  mark  on 


550  MOTION    PICTURE    HANDBOOK 

the  hub  behind  the  head  of  the  pin.  Gear  and  ball  race  may 
now  be  driven  off. 

No.  11.— To  remove  flywheel,  26P,  P.  2,  take  out  screw  in 
end  of  shaft  and  carefully  pry  off  the  cap  under  it,  where- 
upon the  wheel  may  be  pulled  away.  This  also  releases  pin- 
ion 27P,  P.  2  and  3. 

No.  12.— To  remove  bearing  bracket  30P,  P.  3,  which  is 
also  the  oil  well  cover,  follow  instruction  No.  11.  Then  pull 
off  pinion  27P,  P.  3,  remove  screws  867P  (six  of  them),  P.  2, 
whereupon  the  bracket  including  the  cam  34P,  P.  2,  gear  33P, 
P.  2,  and  its  shaft  25P,  P.  2,  can  be  pulled  away  as  a  unit. 
In  removing  this  bracket  pull  the  parts  away  carefully,  mov- 
ing them  straight  outward,  then  up  and  to  the  right,  being 
careful  not  to  strain  any  part,  else  you  may  injure  the  cam 
pin  or  the  star  or  both. 

No.  13.— To  remove  cam  34P,  P.  2,  follow  instructions  Nos. 
11  and  12,  and  drive  out  taper  pin  engaging  the  hub  of  what 
appears  to  be  gear  33P,  P.  2,  but  is  in  reality  the  hub  of  the 
cam.  This  will  release  cam  34P,  P.  2,  and  gear  33P,  P.  2. 
Gear  33P,  P.  2,  is  held  to  cam  34P,  P.  2,  by  four  screws  in  the 
back  of  the  cam;  by  removing  these  screws  the  gear  is 
released. 

No.  14. — Shaft  25P,  P.  2,  runs  in  a  bronze  bushing  pressed 
into  the  bracket  casting  30P,  P.  3.  This  bushing  may  be 
driven  out  and  a  new  one  substituted.  The  new  bushing  may 
be  driven  in  from  either  direction,  but  be  very  careful  that 
you  get  it  started  straight,  and  do  not  use  anything  but  a 
hard  wood  punch  to  drive  it.  Proceed  carefully  and  you 
will  have  no  trouble.  The  inner  end  of  the  bushing  should 
be  flush  with  the  casting. 

No.  15. — To  remove  the  intermittent  unit,  which  includes 
shaft  40P,  P.  2,  star  44P,  P.  2,  bushing  42P,  P.  2,  eccentric 
sleeve  43P,  P.  2,  collar  45P,  P.  2,  and  intermittent  sprocket 
41P,  P.  2,  proceed  as  follows:  Remove  screw  49P,  P.  1,  and 
pull  off  bracket  48P,  P.  1.  Release  screws  833P  (two  of  them), 
P.  1,  and  take  off  intermittent  stripper  52P,  P.  1.  Next  re- 
move screw  201,  P.  2.  Then  raise  up  on  pin  SOP,  P.  1,  which 
revolves  eccentric  sleeve  43P,  P.  1,  and  disengages  the  star 
from  the  cam.  The  intermittent  unit  may  now  be  removed 
by  grasping  the  intermittent  sprocket  and  pulling  straight 
out. 

No.  16. — To  remove  intermittent  sprocket  41P,  P.  2,  follow 
instruction  No.  15  and  then  drive  out  the  two  taper  pins  in 
the  hub  of  the  sprocket.  See  recommendation  in  instruction 
No.  57. 


FOR   MANAGERS   AND    OPERATORS  551 

No.  17. — To  remove  both  bushings  42P,  P.  2,  follow  instruc- 
tion No.  15,  drive  out  taper  pin  in  the  hub  of  star  44P,  P.  2. 
Intermittent  shaft  may  then  be  removed  from  sleeve  43P, 
P.  2.  There  are  two  bushings  in  this  sleeve,  and  to  remove 
them  drive  either  one  clear  in  against!  the  other  bushing 
and  drive  the  old  bushings  right  on  through.  In  putting  in 
new  bushings  us'e  nothing  but  a  hardwood  punch  and  be 
sure  to  get  them  started  straight.  Drive  the  bushings  in  at 
either  end  of  the  sleeve  until  they  are  flush  with  the  face  of 
the  sleeve.  See  recommendation  in  instruction  No.  57. 

No.  18.— The  inner  end  of  shaft  25P,  P.  2,  is  carried  by  a 
small  bronze  bushing.  To  remove  this  bushing  and  to  re- 
place proceed  as  follows:  First  follow  instruction  Nos.  11, 
12  and  15,  which  removes  the  entire  intermittent  mechanism. 
The  hole  which  holds  the  bushing  carrying  the  end  of  shaft 
25P,  P.  2,  extends  clear  through  to  the  other  side,  its  open 
end  being  plugged  up  with  a  loosely  fitting  iron  plug.  Stick 
a  steel  nail  or  any  slim  punch  through  the  bushing  and  drive 
this  plug  out.  Then  the  bushing  may  be  driven  out  from 
either  end  and  the  new  one  driven  in.  In  driving  in  the  new 
bushing  use  nothing  but  a  hardwood  punch,  and  be  sure  to 
get  it  started  straight.  The  new  bushing  may  be  driven  in 
from  either  end  and  its  face  must  be  flush  with  the  casting 
on  the  inside  end. 

No.  19.— Gear  176P,  P.  2  and  its  shaft,  gear  163P,  P.  2; 
belt  wheel  161P,  P.  2;  gear  158P,  P.  2,  and  the  shaft  carrying 
them  may  be  removed  as  a  unit  by  first  disconnecting  the 
motor  and  the  take  up  belts  659P  and  334P,  P.  4,  and  pulling 
out  the  hinge  pins  338P  and  660P,  P.  4,  then  removing  screws 
872P,  P.  2,  and  two  others  in  the  opposite  end  of  plate  181P. 
Next  remove  screw  152P,  P.  1,  and  crank  151 P,  P.  1,  and  the 
taper  pin  in  the  shaft  behind  the  hub  of  the  crank.  Next 
loosen  screw  on  the  inner  end  of  shaft  455P,  P.  1.  This 
screw  is  on  the  gate  side  just  between  sprocket  452P,  P.  1,  and 
the  casting.  Having  released  the  screws,  turn  down  the 
stripper  plate  which  comes  up  between  the  flanges  of  the 
sprocket,  and  then  remove  sprocket  452P,  P.  1,  by  loosening 
the  screw  in  the  center  of  its  hub  and  pulling  the  sprocket 
off  its  shaft;  also  pull  off  collar  which  is  on  the  shaft  behind 
sprocket,  after  loosening  two  set  screws  in  its  hub.  This 
releases  the  parts.  After  having  raised  the  framing  carriage 
as  far  as  it  will  go,  grasp  plate  181P,  P.  2,  and  pull  the  whole 
thing  straight  out  and  away. 

Caution. — In  replacing  this  part  be  careful  when  you  put 
the  lower  sprocket  452P,  P.  1,  back  on  the  shaft  that  it 


552 


MOTION    PICTURE   HANDBOOK 


centers  properly  between  the  flanges  of  the  idler  roller  281P, 
P.  1  (see  instruction  No.  55),  and  that  the  stripper  plate  is 
raised  up  into  position  between  the  flanges  of  the  sprocket, 
and  its  holding  set  screw  well  tightened. 


8OOP 


Plate  2,  Figure  269. 

No.  20. — The  method  of  driving  the  machine  is  as  follows: 
When  crank  driven,  gear  158P,  P.  2,  which  is  attached  to  take 
up  belt  pulley  and  to  the  crank  shaft,  drives  pinion  (stock 
No.  174)  which  is  secured  to  the  lower  sprocket  shaft  170P, 


FOR    MANAGERS   AND    OPERATORS  553 

P.  1.  This  pinion  is  just  inside  the  plate  181 P,  P.  2,  and  does 
not  show.  It  drives  the  lower  sprocket  shaft  and  gear  176P, 
P.  2  and  3,  which  in  turn  drives  the  cam  shaft  through 
pinion  27P,  P.  2  and  3. 

When  the  machine  is  motor  driven,  motor  pulley  625P, 
P.  4,  drives  friction  disc  622P,  P.  4,  which  in  turn  drives  belt 
659P,  P.  4.  Belt  659P,  P.  4,  drives  pinion  163P,  P.  2,  being 
attached  to  pulley  161P,  P.  2.  Pinion  163P,  P.  2,  drives 
lower  sprocket  shaft  gear  176P,  P.  2  and  3.  Gear  176P,  P. 
2  and  3,  then  drives  the  intermittent  movement  through 
pinion  27P,  P.  2  and  3. 

No.  21. — To  remove  gear  176P,  P.  2  and  3,  drive  out  taper 
pin  in  its  hub,  remembering  that  the  file  mark  on  the  hub 
is  at  the  large  end  of  the  pin.  Gear  can  then  be  pulled  off 
the  shaft. 

No.  22.— To  remove  lower  sprocket  shaft  170P,  P.  3,  and 
the  inner  pinion  thereon  follow  instruction  No.  19  and  then 
drive  out  taper  pin  in  hub  of  gear  176P,  P.  2  and  3,  where- 
upon the  shaft  can  be  pulled  out  on  the  operating  side  of 
the  machine. 

No.  23. — To  remove  bronze  bushing  carrying  lower 
sprocket  shaft  170P,  P.  1,  follow  instructions  Nos.  19  and 
21,  whereupon  the  bushing  may  be  driven  out  from  either 
direction,  using  a  hard  wood  block  and  hammer  for  the 
purpose.  In  replacing  this  bushing  take  note  that  the  bush- 
ing is  longer  than  the  bearing,  and  be  careful  that  it  pro- 
jects or  extends  the  same  distance  as  the  old  one. 

No.  24.— To  remove  belt  pulley  161  P,  P.  2,  and  gear  163 P, 
P.  2,  follow  instruction  No.  21  and  then  loosen  set  screws 
(two  of  them),  in  collar  162P,  P.  3,  after  which  the  pulley 
and  gear  can  be  removed. 

No.  25.— To  remove  gear  158P,  P.  2,  and  the  belt  pulley 
attached  thereto,  follow  instruction  No.  19,  and  remove  collar 
163P,  P.  3,  whereupon  the  shaft  and  gears  can  be  pulled  out. 
Gear  158P,  P.  2  and  3,  is  attached  to  the  crankshaft  by 
means  of  a  taper  pin  in  its  hub,  and  the  belt  pulley  next  it 
is  also  attached  in  the  same  manner. 

No.  26. — The  crank  end  of  the  crankshaft  is  supported  by  a 
bronze  bushing.  To  remove  this  bushing  and  replace  it  with 
a  new  one  follow  instruction  No.  19,  whereupon  the  bushing 
may  be  driven  out  from  either  direction  and  the  new  one 
driven  in,  using  only  a  hard  wood  block  for  the  purpose. 

No.  27.— Just  below  the  intermittent  oil  well  in  the  main 
frame  casting  is  one  of  the  bushings  supporting  lower 
sprocket  shaft  170P,  P.  1.  To  remove  this  bushing  and  re- 


554  MOTION   PICTURE   HANDBOOK 

place  it  with  a  new  one  follow  instruction  No.  19,  whereupon 
the  bushing  may  be  driven  out  from  either  direction  and 
the  new  one  driven  in,  using  a  hardwood  block  for  driving. 

No.  28. — The  springs  which  hold  the  idler  roller  bracket 
to  the  sprocket  are  removed  or  attached  merely  by  slipping 
them  off  the  studs. 

No.  29. — To'  remove  governor  bracket  137P,  P.  2  and  3, 
carrying  governor  and  the  center  ball  race  of  shaft  100P, 
P.  2  and  3,  follow  instructions  Nos.  1  and  2,  then  remove 
taper  pin  70P,  P.  2,  and  arm  117P,  P.  2,  and  pull  out  shaft 
116P,  P.  2.  Next  remove  screw  854P,  P.  2,  and  shove  up- 
ward on  gear  103P,  P.  2,  thus  raising  both  the  gear  and  ball 
bearing  above  its  supporting  casting.  Now  remove  screw 
866P,  P.  2  (four  of  them),  whereupon  part  137P,  P.  2  and  3, 
can  be  pulled  away,  carrying  with  it  the  governor,  gear  136P, 
P.  2,  and  link  140P,  P.  2. 

No.  30.— To  remove  castings  IP,  P.  1,  and  2P,  P.  3,  which 
support  the  lens,  follow  instruction  No.  1,  then  take  out 
taper  pin  70P,  P.  2,  pull  out  shaft  116P,  P.  2,  and  remove 
four  screws,  one  at  each  corner  of  the  casting,  first  pulling 
part  2P,  P.  3,  in  by  means  of  knob  10P,  P.  1,  far  enough  to 
expose  the  two  screws  in  the  lens  end  of  the  casting. 

No.  31.— To  remove  knob  10P,  P.  1,  and  rod  9P,  P.  1,  look 
on  the  under  side  of  casting  immediately  below  rod  9P,  P.  1, 
at  the  end  next  knob  10P,  P.  1,  and  you  will  find  a  small 
screw.  This  screw  engages  a  groove  in  shaft  9P,  P.  1,  and 
after  it  has  been  removed,  rod  9P  and  knob  10P  may  be 
removed  by  screwing  it  out  of  the  arm  of  part  2P,  P.  3.  In 
replacing  this  part  do  not  forget  to  tighten  up  this  retaining 
screw  so  that  it  engages  with  the  groove  in  the  shaft,  or  else 
the  rod  will  not  operate  part  2P,  P.  3. 

No.  32.— Part  2P,  P.  3,  is  the  casting  which  engages  or 
grasps  tube  318P,  P.  3,  which  holds  the  lens.  The  lens  tube 
itself  rests  inside  part  318P,  P.  3,  so  that  when  the  parts  are 
assembled  and  the  lens  is  in  place,  part  318P,  P.  3,  and  the 
lens  tube  are  tightly  clamped  together  by  screw  867P,  P.  1 
and  3;  and  since  part  318P,  P.  3,  carries  with  it  shutter  blade 
310P,  P.  2,  and  shutter  shaft  312P,  P.  2  and  3,  it  follows  that 
by  adjusting  knob  10P,  P.  1,  the  lens  and  the  shutter  blade 
are  both  moved  inward  and  outward  when  the  lens  is  focused, 
and  thus  the  shutter  is  maintained  at  all  times  at  a  fixed 
distance  from  the  lens. 

No.  33.— Top  guide  roller  19P,  P.  1,  is  composed  of  inner 
flange  18P,  P.  3,  outer  flange  20P,  P.  3,  and  spreading  rollers 
19P,  P.  1,  these  being  held  together  by  spindle  14P,  P.  3, 


FOR   MANAGERS   AND    OPERATORS 


555 


and  spring  16P,  P.  3.  This  part  may  be  dissembled  by  re- 
moving set  screw  in  the  supporting  casting  just  back  of 
arrow  head  18P,  P.  3.  The  tension  of  spring  16P,  P.  3,  may 
be  varied  at  will  by  loosening  the  holding  set  screw  just 
back  of  arrow  head  18P,  P.  3,  and  moving  shaft  14P,  P.  3, 
slightly  in  or  out. 


Plate  3,  Figure  270. 

• 

No.  34. — Aperture  plate  5P,  P.  1,  is  held  in  position  by  four 
screws.  This  plate  is  made  of  carbon  steel  as  hard  as  glass. 
It  may  be  removed  for  renewal  by  taking  out  four  screws, 
one  in  each  corner. 


556  MOTION    PICTURE   HANDBOOK 

No.  35. — To  remove  gate  80P,  P.  1,  take  out  the  four 
screws  holding  the  main  casting  to  the  posts  and  then  pull 
the  gate  away.  The  hinges  are  held  by  dowel  pins  in  ad- 
dition to  the  screw. 

No.  36. — Automatic  fire  shutter  flap  91 P,  P.  2,  is  attached 
to  its  shaft  merely  by  being  bent  around  it.  Its  position  on 
the  shaft  may  be  adjusted  by  holding  horizontal  rack  88P, 
P.  1,  stationary  and  lifting  or  lowering,  as  the  case  may  be, 
fire  flap  91P,  P.  2.  Fire  flap  91  P,  P.  2,  may  be  removed  by 
driving  out  the  spindle  from  the  pinion  end.  In  replacing 
hold  the  corner  of  a  hardwood  block  against  the  pinion  and 
drive  the  shaft  into  the  pinion,  after  having  shoved  the  shaft 
through  the  fire  flap.  The  rack  engaging  this  pinion  may 
be  removed  by  driving  it  through  the  gate  away  from  the 
pinion;  use  only  a  hardwood  punch  for  this  purpose,  the 
door  of  course  being  open  or  off  the  machine.  This  rack 
should  be  kept  clean  and  perfectly  free  at  all  times,  since 
the  shutter  drops  by  gravity  alone. 

No.  37. — Each  of  tension  shoes  65P,  P.  1,  is  pivoted  to  a 
plunger  which  passes  through  the  gate  casting,  the  shoes 
being  held  up  against  the  film  by  a  flat  spring,  the  lower  end 
of  which  is  seen  at  66P,  P.  1.  The  tension  on  this  spring  is 
regulated  by  nut  68P,  P.  2,  which  is  attached  to  a  steel  screw 
67P,  P.  1.  Thus  the  operator  at  all  times  is  able  to  give  his 
tension  the  finest  possible  adjustment.  Spring  66P,  P.  1,  is 
so  pivoted  that  it  automatically  equalizes  the  tension  between 
the  two  shoes. 

Lower  tension  shoes  55P,  P.  1,  are  attached  to  plate  58P, 
P.  1,  and  are  held  up  by  a  small  flat  yoke  spring  at  its  rear. 
Plate  58P,  P.  1,  and  lower  tension  shoes  55P,  P.  1,  may  be 
removed  by  taking  out  screw  878P,  P.  1,  on  the  upper  end 
of  the  plate.  Upper  tension  shoes  65P,  P.  1,  may  be  removed 
by  pressing  in  on  the  lower  end  of  the  shoe  until  the  upper 
end  comes  out  of  its  engaging  slot;  turn  upper  end  toward 
center  of  the  gate.  It  will  then  be  released  from  its  pivot 
pin. 

No.  38.— Spring  94P,  P.  1,  is  held  by  two  screws  at  its 
lower  end,  and  serves  to  hold  the  film  over  against  the  steel 
track  at  the  left  of  the  aperture.  It  also  prevents  side  mo- 
tion. The  main  tension  spring  supplies  tension  tfi  the  upper 
shoes.  To  remove  this  spring,  remove  screw  72P,  P.  2,  in 
the  center  of  nut  68P,  P.  2,  taking  off  nut  68P,  P.  2,  and 
pulling  out  pin  67P,  P.  1.  In  replacing  the  spring  be  sure 
that  the  depression  in  its  face  rests  on  the  fulcrum  properly 


FOR   MANAGERS   AND    OPERATORS  557 

and   that   its   upper   ends    engage   with   the   plungers   of   the 
tension  shoes. 

No.  39 — Upper  sprocket  452P,  P.  1,  may  be  removed  by 
loosening  the  screw  holding  stripper  spindle  454P,  P.  1  and  3. 
Swing  the  stripper  up  out  of  the  way,  loosen  the  set  screw 
in  the  hub  of  the  sprocket,  and  pull  sprocket  off.  In  re- 
placing sprocket  be  careful  to  get  it  properly  centered  be- 
tween the  flanges  of  its  idler  rollers. 

No.  40.— Upper  sprocket  shaft  450P,  P.  1  and  3,  and  gear 
451P,  P.  2  and  3,  may  be  removed  by  following  instruction 
No.  39  and  then  removing  collar  453P,  P.  1,  by  loosening 
set  screws  (two  of  them)  in  its  hub,  afterward  pulling  shaft 
and  gear  out. 

No.  41. — To  remove  gear  HOP,  P.  2,  drive  out  the  taper 
pin  in  its  hub  and  raise  the  gear  off  by  revolving  it  until  it 
disengages  from  the  teeth  of  451P,  P.  2  and  3. 

No.  42.— To  remove  shaft  100P,  P.  2  and  3,  remove  screw 
in  top  of  mechanism  which  engages  main  supporting  spring 
217P,  P.  1,  then  remove  nuts  223P,  P.  3,  and  take  out  the 
two  top  screws  holding  machine  case  to  the  top  of  mechan- 
ism, which  will  allow  the  whole  top  of  the  machine  to  be 
taken  off.  Next  release  screw  854P,  P.  2,  and  upper  and 
lower  screws  868P,  P.  2.  Now  follow  instruction  No.  12, 
look  into  the  oil  well  and  see  the  bevel  gear  on  lower  end 
of  shaft,  attached  thereto  by  a  taper  pin,  remembering  that 
the  file  mark  is  at  the  large  end  of  the  pin.  Drive  this  pin 
out.  Next  loosen  two  set  screws  in  collar  resting  on  part 
203P,  P.  2,  and  215P,  P.  2,  whereupon  shaft  100P,  P.  2,  may 
be  lifted  out  upward. 

No.  43. — The  mechanism  is  held  to  the  lower  magazine 
by  four  screws,  the  heads  of  which  are  seen  by  looking 
underneath  the  edge  of  the  casting  in  the  top  of  the  lower 
magazine.  Remove  these  four  screws  and  you  may  lift  the 
whole  mechanism  away. 

No.  44. — The  framing  of  the  carriage  is  accomplished  by 
means  of  a  segment  of  a  gear  and  pinion  attached  to  the 
side  of  the  base  of  the  mechanism.  Should  anything  at  any 
time  go  wrong  with  this  mechanism  you  can  get  at  it  by 
removing  the  -machine  from  the  base,  whereupon  its  method 
of  dissembling  is  self-evident.  The  framing  mechanism 
under  the  base  operates  a  vertical  screw  247P,  P.  4,  which 
engages  with  a  phosphor  bronze  nut  attached  to  the  center 
of  the  framing  carriage. 

No.  45. — The  weight  of  the  framing  carriage  is  carried  by 


558  MOTION   PICTURE   HANDBOOK 

a  vertical  spring  217P,  P.  1,  and  if  there  is  a  tendency  for  the 
carriage  to  work  down  proceed  as  follows:  Open  the  motor 
compartment  door,  and  looking  up  at  the  bottom  of  the 
mechanism  you  will  see  a  half  round  arrangement  with  a 
cap  and  three  screws;  this  is  open  at  one  side.  Looking 
in  you  will  see  a  small  nut  which  has  a  right-hand  thread. 
By  tightening  this  nut  slightly  the  tension  on  the  framing 
handle  is  increased.  Later  design  has  a  plate  supported  by 
two  lugs  in  place  of  the  half  round  support,  the  adjustment 
being  the  same. 

No.  46.— Where  it  is  desirable  to  use  half-size  lens  the 
company  furnishes  a  special  mount  with  a  revolving  shutter. 
The  half-size  lens  cannot  be  used  with  the  regular  mount  as 
shown  at  318P,  P.  1  and  3. 

No.  47. — To  remove  motor  drive  unit  disconnect  wires 
leading  to  switch  and  remove  belt  659P,  P.  4,  by  taking  out 
pin  669P,  P.  4.  Looking  under  casting  621 P,  P.  4,  you  will 
see  a  horizontal  link  connected  to  a  vertical  lever  by  a  screw. 
Remove  this  screw.  Next  take  off  nut  securing  upper  end  of 
toggle  link  to  casting  621P,  P.  4.  Remove  screw  658P,  P.  4. 
Motor  unit  may  now  be  taken  out  as  a  whole.  Motor  may 
be  removed  from  casting  621  P,  P.  4,  by  removing  screws  in 
bottom  of  casting  621P,  P.  4,  and  screws  in  coupling  650P, 
P.  4. 

No.  48. — In  order  to  remove  driving  friction  wheel  which 
bears  on  friction  disc  622P,  P.  4,  first  follow  instruction  No. 
47,  then  remove  638P,  P.  4,  from  shaft  635P,  P.  4.  This 
key  is  held  in  position  by  a  screw  in  its  face.  Next  remove 
three  screws  in  the  face  of  the  leather  washer  633P,  P.  4, 
which  will  release  disc  wheel. 

No.  49. — To  remove  the  friction  material  on  face  of  625P, 
P.  4,  follow  instructions  Nos.  47  and  48  and  then  remove 
screws  in  the  outer  end  (you  cannot  see  them  in  the  cut) 
of  the  friction  wheel.  This  releases  the  friction  material, 
which  may  be  removed  and  new  material  be  secured  from 
the  manufacturer  and  put  in  its  place.  The  friction  material 
will  need  no  turning  or  trueing  up  after  being  put  in. 

No.  50.— To  remove  disc  wheel  622P,  P.  4,  release  the  set 
screw  in  the  belt  pulley  on  the  shaft  of  the  disc,  after  first 
having  released  the  screw  in  the  rim  of  knurled  adjusting 
nut  on  the  rear  end  of  the  shaft.  Back  this  nut  off,  where- 
upon you  may  pull  the  friction  disc  and  shaft  away. 


FOR   MANAGERS   AND    OPERATORS  559 

ADJUSTMENTS. 

No.  51. — To  adjust  the  intermittent  sprocket  and  cam  in 
order  to  eliminate  lost  motion  in  the  intermittent,  first  loosen 
screw  201 P,  P.  2,  and  screw  49P,  P.  1,  after  which  slightly 
turn  eccentric  sleeve  43P,  P.  1,  by  pressing  down  on  pro- 
jecting pin  SOP,  P.  1,  at  the  same  time  revolving  the  fly- 
wheel by  hand.  When  you  think  you  have  it  just  about 
right  tighten  up  screw  201P,  P.  2,  and  try  the  intermittent 
sprocket  with  your  fingers.  See  General  Instruction  No.  5. 
When  you  have  the  adjustment  made  to  your  satisfaction 
tighten  up  screw  49P,  P.  1,  and  the  adjustment  is  completed. 

Caution:  Should  you,  for  any  reason,  remove  bracket  48P, 
P.  1,  be  very  sure  that  its  face  and  the  face  it  fits  on  arc 
perfectly  clean  when  you  put  them  back,  because  dirt  might 
and  probably  would  throw  the  part  out  of  line  and  cause 
shaft  40P,  P.  1,  to  bind  in  bushing  42P,  P.  1.  Also  be  very 
sure  that  screw  201P,  P.  2,  is  set  up  tight.  If  it  is  not  it  will 
cause  trouble. 

No.  52. — End  motion'  in  the  intermittent  sprocket  (see 
General  Instruction  No.  7)  may  be  removed  by  loosening  the 
screw  in  the  steel  collar  between  intermittent  sprocket  41P, 
P.  1,  and  eccentric  sleeve  43P,  P.  1,  and  prying  lightly 
against  the  rim  of  the  sprocket  with  a  screwdriver,  letting 
the  point  of  the  screwdriver  rest  on  the  collar,  which  will 
have  the  effect  of  forcing  the  sprocket  to  the  right  and  the 
collar  to  the  left.  Tighten  up  the  screw  in  the  collar  while 
it  is  held  in  this  position. 

No.  53. — In  threading  the  machine,  when  you  raise  the 
lower  sprocket  idler  do  not  jerk  it  up  as  though  you  were 
working  with  a  two-inch  bar.  Rough  handling  of  this  idler 
may  get  it  out  of  line  with  the  sprocket,  which  will  cause 
the  losing  of  the  lower  loop.  (See  General  Instruction  No. 
12.) 

No.  54.— The  quantity  of  oil  in  oil  well  213P,  P.  2,  should 
only  be  sufficient  so  you  can  see  the  oil  splash  on  the. 
oil  window  when  the  machine  is  running.  In  order  to  clean 
out  oil  well  213P,  P.  2,  remove  the  screw  immediately  below 
the  glass  window,  which  will  allow  the  oil  to  drain  out,  you 
of  course  providing  something  for  the  oil  to  run  into.  Re- 
place the  screw,  flood  the  well  with  kerosene,  and  give  the 
machine  a  few  turns,  after  which  remove  the  screw,  drain 
out  the  kerosene  and  put  in  fresh  oil.  (See  General  Instruc- 
tion No.  1.) 


560 


MOTION    PICTURE   HANDBOOK 


No.  55. — With  regard  to  the  idler  rollers  (see  General  In- 
struction No.  12),  in  order  to  change  the  distance  of  idler 
rollers  from  the  sprocket,  loosen  the  clamping  screw  in  the 


Plate  4,  Figure  271. 

hub  of  bracket,  one  of  which  is  shown  at  800P,  P.  1,  which 
will  allow  of  moving  the  bracket  on  its  shaft.  In  making  this 
adjustment  be  very  careful  not  to  move  the  hub  of  bracket 


FOR    MANAGERS   AND    OPERATORS  561 

away  from  the  main  casting,  which  would  cause  the  idler  to 
be  out  of  line  with  the  intermittent  sprocket. 

No.  56.— Upper  and  lower  sprockets  may  be  turned  end  for 
end  on  their  shafts  in  order  to  present  a  new  tooth  surface 
to  the  film,  if  the  teeth  are  worn  on  one  side. 

No.  57. — I  would  by  all  means  advise  all  purchasers  of  the 
Baird  machine  either  at  the  time  of  purchase  or  later  on  to 
secure  a  complete  part  comprised  of  40P,  41P,  51P,  42P  and 
44P,  P.  2.  Then  when  your  intermittent  sprocket,  shaft,  bush- 
ing or  star  is  worn,  all  you  have  to  do  is  to  remove  the  complete 
part,  substitute  the  new  one  and  send  the  old  one  to  the 
factory  for  inspection  and  repairs.  This  is  in  every  way 
much  better  than  to  attempt  to  put  on  a  new  intermittent 
sprocket.  The  intermittent  sprocket  is  the  heart  of  a  mov- 
ing picture  machine,  and  it  must  not  only  be  true  down  to 
as  little  as  one  ten-thousandth  of  an  inch,  but  it  must  be 
mounted  absolutely  true  also,  and  the  operator  is  seldom 
in  a  position  to  do  a  delicate  job  of  this  kind  properly. 

No.  58.— The  wear  of  the  bushing  carrying  shaft  170P,  P.  1, 
supporting  lower  sprocket  452P,  P.  1,  will  have  the  effect  of 
increasing  the  distance  between  the  sprocket  and  its  idler. 
Should  you  begin  to  have  trouble  with  losing  the  lower  loop, 
first  see  if  you  can  move  the  outer  end  of  the  lower  sprocket 
up  and  down  perceptibly.  If  you  can,  the  bushing  is  prob- 
ably somewhat  worn  and  the  distance  between  sprocket  and 
idler  has  increased.  The  remedy  is  to  loosen  the  idler.  (See 
Instruction  No.  55.)  When  you  are  making  this  adjustment 
hold  down  on  the  sprocket;  then  adjust  idler  roller  to  suit 
this  condition. 

No.  59. — There  should  be  just  sufficient  pressure  between 
friction  disc  wheel  622P,  P.  4,  and  driving  friction  wheel  to 
cause  disc  wheel  622P,  P.  4,  to  continue  to  revolve  when  belt 
659P,  P.  4,  is  slipping  on  pulley.  This  pressure  is  regulated 
by  a  knurled  nut  at  the  rear  end  of  the  shaft,  carrying  disc- 
wheel  622P,  P.  4.  To  test  the  drive,  start  the  motor  and 
grasp  the  flywheel  firmly,  causing  the  belt  to  slip  on  the 
pulley.  Any  unnecessary  pressure  between  friction  disc- 
wheel  622P,  P.  4,  and  the  driving  friction  wheel  will  cause 
excessive  wear  and  loss  of  power  and  probably  heating 
of  the  motor. 

No.  60. — At  the  lower  end  of  rod  639P,  P.  4,  is  a  casting 
supported  by  a  stud  attached  to  the  rear  wall  of  the  com- 
partment. This  casting  is  supported  on  the  stud  by  a  clamp 
lined  with  fibre.  Should  at  any  time  the  knob  512P,  P.  4. 


562  MOTION    PICTURE    HANDBOOK 

develop  a  tendency  to  work  up  or  down  while  the  motor  is 
running,  tighten  the  screw  in  this  clamp  bushing  sufficiently 
to  hold  the  rod  in  place  and  prevent  the  knob  from  moving 
through  vibration  of  parts. 

No.  61. — On  the  operating  side  of  the  machine  at  the  bot- 
tom of  the  magazine  is  a  horizontal  lever,  the  purpose  of 
which  is  to  raise  the  discwheel  end  of  part  621P,  P.  4,  thus 
releasing  belt  659P,  P.  4,  which  operates  as  follows:  When 
ready  to  start  the  show  raise  the  lever  up  and  start  your 
motor  by  throwing  in  the  handle  of  switch  329P,  P.  4,  next 
set  speed  regulating  knob  512P,  P.  4,  in  running  position, 
if  it  is  not  already  there.  Now  when  you  are  ready  to  pro- 
ject the  picture  drop  the  lever  slowly  down  with  one  hand 
and  as  the  fire  shutter  raises  raise  the  dowser  with  the  other 
hand. 

No.  62.— Belt  334P,  P.  4,  operates  the  take-up.  The  take-up 
gear  342P,  P.  4,  is  on  take-up  spindle,  348P,  P.  4,  which  carries 
the  lower  reel.  This  spindle  is  supported  by  bar  346P,  P.  4, 
which  is  hinged  to  the  machine  casting  on  the  opposite 
side,  just  back  of  the  figures  342P,  P.  4.  The  front  end 
of  this  lever,  including  the  take-up  spindle,  rests  in  and 
is  supported  by  belt  334P,  P.  4.  Th6  result  is  that  when  the 
reel  in  the  take-up  magazine  is  empty  there  is  very  little 
friction  on  this  belt,  but  as  the  film  is  wound  on  the  reel 
the  weight  increases,  and  thus  an  automatically  regular  take- 
up  tension  is  supplied  in  excellent  form. 

No.  63. — Any  angle  may  be  given  the  machine  as  a  whole 
by  loosening  the  clamps  which  secure  the  legs  and  raising 
or  lowering  the  machine  to  secure  the  desired  setting. 

No.  64. — The  condenser  is  supported  in  a  metal  casing 
which  forms  a  heat  reservoir  and  will  go  far  toward  reduc- 
ing lens  breakage.  The  casing  is  so  designed  that  it  may 
be  adjusted  to  suit  various  conditions.  It  is  advisable  that 
the  lens  be  kept  about  one-sixteenth  of  an  inch  apart. 

No.  65. — On  the  top  of  the  carbon  clamp  of  your  lamp, 
under  the  clamping  screw,  is  a  hole  which  should  be  kept 
filled  with  powdered  graphite  at  all  times.  Do  this  and  you 
will  have  no  trouble  with  your  carbon  clamp  screws  working 
hard. 

No.  66. — The  cups  on  the  motor  should  be  kept  filled  with 
a  good  grade  of  medium  oil. 


FOR    MANAGERS   AND    OPERATORS 


563 


NAMES  AND   NUMBERS   OF   PARTS   FOR 
BAIRD  MACHINE 

Order  parts  by  number  only.  These  numbers  are  the 
manufacturers'  regular  stock  numbers.  The  first  column  in- 
dicates the  number  of  the  plate  or  plates  upon  which  the 
part  appears. 


Pin  to  adjust  eccen- 
tric sleeve. 

Gasket  for  eccentric 
sleeve. 

Stripper  for  inter- 
mittent sprocket. 

Lower   tension    shoe. 

Spring  for  lower  ten- 
sion shoe. 

Upper    tension    shoe. 

Spring  for  upper  ten- 
sion shoe. 

Adjusting  screw  for 
upper  tension  shoe. 

Adjusting  nut  for 
upper  tension  shoe. 

Screw  stop  for  ad- 
justing nut  for  up- 
per tension  shoe. 

Gate. 

Spring  for  locking 
pin  on  gate  door. 

Plunger  for  locking 
gate  door. 

Pin  for  releasing  lock- 
ing plunger  on  gate 
door. 

Foot  on  gate  door 
plunger. 

Knob  for  releasing 
pin  on  gate. 

Rack  for  fire  shutter. 

Pinion  for  fire  shut- 
ter. 

Shaft  for  fire  shutter. 

Fire    shutter. 

Hinges. 

Spring  for  edge  of 
film. 

Vertical  shaft. 

Bevel  gear  on  lower 
end  of  vertical 
shaft. 

Bevel  gear  on  center 
of  vertical  shaft  for 
D.  C.  machine.  . 

Ball  bearing  for  cen- 
ter bevel  gear  on 
vertical  shaft. 

Bevel  gear  on  center 
of  vertical  shaft  for 
A.  C.  machine. 

Nut  for  center  bevel 
gear  on  vertical 
shaft. 


1 

—     IP 

Bracket  for  lens  and 

2        —  50P 

aperture  plate. 

3 

—     2P 

Slide  for   %   size  lens 

2         —  51P 

and    shutter    guard. 

1 

—     5P 

Aperture  plate. 

1         —  52P 

3 

—     7P 

Spring    between    lens 

bracket   and   slide. 

1         —  55P 

1 

—     8P 

Frame   to  hold   glass 

—  59P 

on  lens  bracket. 

3 

&  1—     9P 

Screw  to  adjust  lens. 

1         —  65P 

1 

—  10P 

Knob   of  lens  adjust- 

1        —  66P 

ing  screw. 

3 

—  IIP 

Glass  for  lens  bracket. 

1          -  67P 

3 

—  14P 

Pin    for    film    guiding 

roller. 

2         —  68P 

3 

—  16P 

Spring  for  film  guid- 

ing roller. 

2         —  72P 

3 

-  18P 

Roller  for  back  edge 

of   film. 

1 

—  19P 

Spreader     roller     for 

1         —  SOP 

guiding  film. 

—  81P 

3 

—  20P 

Roller  for  front  edge 

of  film. 

1          —  84P 

2 

—   25P 

Cam   shaft. 

—  26P 

Fly   wheel. 

-  85P 

3 

&  2—  27P 

Pinion  for  cam  shaft. 

—  28P 

Washer  for  fly  wheel. 

—  29P 

Screw      to      hold      fly 

1         —  86P 

wheel       pinion       on 

cam   shaft. 

2         —  87P 

3 

&  2—  SOP 

Bracket    for     outside 

bearing       on       cam 

1         —  88P 

shaft  —  'cover  for   oil 

2         —  89P 

well. 

3 

—  31P 

Bushing    for    outside 

2         —  90P 

bearing       on       cam 

—  91P 

shaft. 

1  &  2-^  92P 

3 

—  32P 

Gasket        for        cam 

1         —  94P 

shaft  bearing. 

2 

—  33P 

Bevel    gear    on    cam 

3  &  2—  100P 

shaft. 

—  101P 

2 

—  34P 

Cam. 

1 

&  2  —  40P 

Intermittent     shaft. 

1 

—  41P 

Intermittent  sprocket. 

2         —  10  3P 

2 

&  1  —  42P 

Bushings     for     inter- 

mittent   shaft. 

1 

—  43P 

Eccentric    sleeve. 

—  104P 

2 

—  44P 

Star  wheel. 

2 

—  45P 

Collar     on     intermit- 

tent  shaft. 

3         —  105P 

1 

—  48P 

Bracket     for    outside 

bearing     on      Inter- 

mittent  shaft. 

3         —  106P 

1 

—  49P 

Screw  for  bracket  on 

intermittent     shaft. 

564 


MOTION    PICTURE   HANDBOOK 


2 

—  107P 

2 

—HOP 

2 

—  112P 

1 

—  115P 

2 

—  116P 

2 

—  117P 

3 

—  130P 
—  131P 

—  132P 

2 

—  134P 

—  135P 

2 

—  136P 

3 

—  137P 

3 

—  138P 

—  139P 

2 

—  14  OP 

2 

—  141P 

—  142P 

2 

—  143P 

2 

—  144P 

2 

3 
1 

1 

—  145P 
—  146P 
—  150P 
—  151P 
—  152P 

—  155P 

3 

—  157P 

3  <• 

fc  2—  158P 

3  &  2—  160P- 

2 

—  161P 

3 

^162P 

2 

—  163P 

Driving  collar  on 
vertical  shaft. 

Gear  on  top  end  of 
vertical  shaft. 

Bushing  for  top  end 
of  vertical  shaft. 

Lever  engaging  fire 
shutter  rack. 

Shaft  carrying  levers 
operating  fire  shut- 
ter. 

Lower  lever  opera- 
ting fire  shutter. 

Governor  shaft. 

Pins  for  governor 
balls. 

Pins  for  collars  on 
governor  shaft. 

Spring  for  governor 
for  D.  C.  machine. 

Bevel  gear  on  gov- 
ernor shaft  for  A. 
C.  machine. 

Bevel  gear  on  gov- 
ernor shaft  for  D. 
C.  machine. 

Bracket  carrying  gov- 
ernor shaft. 

Ball  bearings  on  gov- 
ernor shaft. 

Spring  for  governor 
for  A.  C.  machine. 

Link  connecting  gov- 
ernor and  flre  shut- 
ter. 

Screws  to  guide  gov- 
ernor connecting 
link. 

Sleeve  on  governor 
shaft. 

Fixed  collar  on  gov- 
ernor shaft. 

Sliding  collar  on  gov- 
ernor shaft. 

Balls  for  governor. 

Arm   for    governor. 

Crank  handle  shaft. 

Crank  arm. 

Screw  to  hold  crank 
arm. 

Driving  pin  In  crank 
handle  shaft. 

Pulley  on  crank  han- 
dle shaft. 

Helical  gear  tern  crank 

handle  shaft. 
-Oil     cup    on    end    of 
crank  handle  shaft. 

Pulley  for  motor  belt 
on  crank  handle 
shaft. 

Collar  on  crank 
handle  shaft. 

Pinion  on  crank 
shaft  for  motor 
drive. 


2  — 164P 

1         — 170P 
— 174P 

3  &  2— 176P 

— 181P 
— 185P 

— 186P 


— 2  OOP 
— 201P 


—  202P 
2         —  203P 

—  205P 

—  206P 

—  207P 

2  &  3—  209P 

—  210P 

—  211P 

2  &  3—  212P 
2         —  213P 


2  —  215P 

1         —  217P 

—  220P 

3  &  2—  223P 

—  224P 


— 230P 
— 236P 

— 237P 
— 249P 
— 251P 

— 253P 
— 254P 
— 256P 


Bushings    for  pinions 

on      crank      handle 

shaft. 

Lower  sprocket  shaft. 
Pinion        on        lower 

sprocket  shaft. 
Helical  gear  on  lower 

sprocket  shaft. 
Bracket  for  carrying 

lower  driving  gears. 
Bushing  for  gear  end 

of      crank      handle 

shaft. 
Bushing  for  gear  end 

of     lower     sprocket 

shaft. 

Sliding  main  frame. 
Screw   to  lock  eccen- 
tric   sleeve. 
Bushing     for      inside 

bearing       on       cam 

shaft. 
Bushing      for      lower 

end        of        vertical 

shaft. 
Bushing      for      upper 

sprocket   shaft. 
Bushing      for      crank 

end  of  crank  handle 

shaft. 
Bushing  for  sprocket 

end  of  lower  sprock- 
et shaft. 

Hook  pins  for  brack- 
et  springs. 
Nut  for  framing. 
Plug    for    cam    shaft 

bearing  hole. 
Spring     for     sprocket 

brackets. 
Glass  in   front    of   oil 

chamber. 
Glass    in    top    of    oil 

Chamber. 
Cup    for    bushing    on 

lower    end    of    ver- 
tical  shaft. 
Spring       to       support 

main    frame. 
Post      carrying     gate 

door. 

Nuts  for  top  of  posts. 
Nut     for     bottom     of 

posts. 

Post  for  front  end. 
Rollers  for  upper  and 

lower  flre   valves. 
Pins     for    upper    flre 

valve  rollers. 
Pinion      on      framing 

screw. 
Spring      on      framing 

screw. 

Gear   for  framing 
Handle  for  framing. 
Bracket        for        flre 

rollers,   front. 


FOR    MANAGERS    AND    OPERATORS 


565 


— 257P 

— 258P 

— 259P 

3  &  1— 280P 


—  281P 

—  282P 

—  283P 

—  284P 


—  290P 
1         —  292P 
1         —  300P 

1         —  301P 
1         —  302P 

1  —  303P 

2  —  310P 

—311P 

2  &  3—  312P 

—  313P 

1  &  3—  318P 

3  —  319P 

—  320P 

—  321P 


— 329P 
— 334P 

— 336P 

— 337P 
— 338P 

— 339P 
— 340P 
— 341P 
— 342P 

— 346P 
— 34«P 


Pins  for  lower  fire 
valve. 

Bracket  for  fire 
rollers,  rear. 

Fibre  washer  for 
framing  screw. 

Bracket  carrying 

roller  for  upper 
sprocket. 

Rollers  for  upper  and 
lower  sprockets. 

Arm  for  spring  on 
roller  bracket  shaft. 

Nut  for  sprocket 
roller  shaft. 

Shaft  for  upper  and 
Lower  sprocket  roll- 
ers. 

Bracket  carrying  roll- 
er for  lower  sprocket. 

Shaft  for  bracket 
for  lower  sprocket. 

Bracket  carrying  roll- 
er for  intermittent 
sprocket. 

Shaft  for  roller  for 
intermittent  sprock- 
et. 

Shaft  for  bracket  for 
intermittent  sprock- 
et. 

Roller  for  Intermit- 
tent sprocket. 

Shutter  for  D.  C. 
machine. 

Hub   for  shutter. 

Shaft  for  shutter. 

Washer  clamp  for 
shutter. 

Tube  carrying  lens. 

Casing  for  ball  bear- 
ing. 

Ball    bearing. 

Shutter  for  A.  C. 
machine. 

Switch   for  motor. 

Belt  to  drive  lower 
reel. 

Door  for  motor  com- 
partment. 

Fastener  for  belt. 

Rawhide  pin  for  belt 
fastener. 

Rivets  for  driving 
belt. 

Stationary  bracket 
carrying  lamphouse. 

Track  bars  for  sta- 
tionary bracket. 

Gear  on  lower  reel 
sfhaft  for  small  reel 
1%  core. 

Gear  and  pulley  for 
driving  lower  reel. 

Arm  carrying  lower 
reel. 


4  — 348P 
4  — 349P 

— 350P 
— 351P 
— 352P 
— 353P 
— 354P 
4  — 357P 

3  — 358P 

4  — 360P 
1  &  3 — 450P 
3  &  2— 451P 

1  — 452P 
— 453P 

3  &  1— 454P 
3  &  1 — 455P 
3  — 465P 

2  — 468P 

2  — 469P 
2  — 470P 
2  &  3 — 471P 

2  — 472P 

3  — 473P 


— 476P 
— 480P 
— 481P 

— 482P 
— 6  2  IP 

— 622P 
— -623P 

— 624P 
— 625P 


Shaft   for  lower  reel. 

Pin  carrying  pulley 
on  lower  reel  arm. 

Collar  on  lower  reel 
shaft. 

Latch  for  lower  reel 
shaft. 

Plunger  in  lower  reel 
shaft. 

Spring  in  lower  reel 
shaft. 

Pin  for  latch  in 
lower  reel  shaft. 

Guard  for  belt  on 
arm  carrying  lower 
reel. 

Lug  for  hinge  on 
stand. 

Bracket  for  motor 
switch. 

Shaft  for  upper 
sprocket. 

Gear  on  upper 
sprocket  shaft. 

Upper  sprocket  and 
lower. 

Collar  on  upper 
sprocket  shaft. 

Shaft  for  upper 
sprocket  stripper. 

Stripper  for  upper 
sprocket  and  lower. 

Main  arm  carrying 
stereopticon. 

Coupling  between 
stereopticon  arm 
and  lens. 

Rack  for  stereop- 
ticon arm. 

Rod  for  stereopticon 
arm. 

Knob  for  adjusting 
stereopticon. 

Pinion  for  stereop- 
ticon. 

Pivot  pins  for  stere- 
opticon rack. 

Yoke  end  for  stere- 
opticon. 

Collar  on  stereopticon 
rack. 

Housing  for  stereop- 
ticon lens. 

Retaining  ring  for 
2%"  stereopticon 
lens. 

Stereopticon  lens 

2%" 

Frame  for  friction 
drive. 

Friction  driven  disc. 

Hub  for  driving  fric- 
tion wheel. 

Arm  for  moving  driv- 
ing friction  wheel. 

Face  for  driving  fric- 
tion wheel. 


566 


MOTION    PICTURE   HANDBOOK 


4 

—  626P 

Pivot  base  for  motor 

4 

—  652P 

frame. 

—  627P 

Clamp  washer  for  face 

4 

—  653P 

of    driving    friction 

wheel. 

4 

—  ,659P 

—  628P 

Pulley     on     shaft     of 

4 

—  660P 

driven  friction  disc. 

—  629P 

Bushing     for     driven 

2  1 

3  —  800P 

friction  disc  shaft. 

2 

—  822P 

—  630P 

Bushing        for       ball 

1 

—  827P 

bearing        end        of 

1 

-^829P 

driven  friction  disc. 

—  801P 

—  631P 

Bushing    for    driving 

1 

—  833P 

shaft       on       motor 

2 

—  853P 

drive. 

2 

—  854P 

—  632P 

Adjusting      nut      for 

3  & 

2  —  867P 

driven  friction  disc. 

2 

—  868P 

4 

—  633P 

Retaining   washer   on 

2 

—  872P 

hub  of  driving  fric- 

1 

—  S96P 

4 

—  635P 

tion  wheel. 
Shaft       for       driving 

1 

—  <906P 

friction    wheel. 

2 

—  866 

4 

—  639P 

Friction       lever       for 

2 

—  70 

moving           friction 

3 

—801 

wheel. 

4 

—  6  5  OP 

Leather       band       for 

4 

—  122 

flexible    coupling. 


Rod  for  speed  con- 
trol. 

Ball  bearings  for 
friction  drive. 

Belt  for  motor  drive. 

Rawhide  pin  for  driv- 
ing belt  fastener. 

Clamp    screws. 

Stock  screw. 

Stock  screw. 

Stock  screw. 

Clamping   screw. 

Machine  screw,  stock. 

Stock  macQiine  screw. 

Stock  machine  screw. 

Stock  machine  screw. 

Stock  machine  screw. 

Stock  machine  screw. 

Stock  machine  screws. 

Stock  machine  screw. 
Stock  machine  screw. 

Pin. 

Nut  holding  housing 
480  to  yoke  475. 

Pin  for  hinge  of  door 
336. 


American  Standard— " Master  Model" 

No.  1.— To  Remove  the  Gate,  loosen  screw  525,  P.  1,  and 
pull  shaft  506,  P.  3,  out  to  the  right.  In  order  to  get  at  screw  525, 
P.  1,  it  may  be  necessary  to  take  the  mechanism  loose  from 
its  base  and  stick  a  screwdriver  up  through  a  hole  in  base 
casting  immediately  under  the  screw.  Before  starting  to 
take  off  the  gate,  drop  the  framing  carriage  clear  down,  or 
else  the  gate  will  not  pass  the  film  chute. 

No.  2. — To  Remove  the  Lower  Sprocket  Film  Chute,  A-P 
17,  P.  2,  and  gear  454,  P.  2,  first  follow  Instruction  No.  1, 
then  drive  out  the  taper  pin  iri  the  center  of  the  hub  of  lower 
sprocket,  443,  P.  2,  and  the  taper  pin  in  the  hub  of  gear  454, 
P.  2.  You  can  then  pull  the  shaft  ut  to  the  left,  driving  it 
with  a  copper  punch  if  necessary.  Be  sure  and  drive  the 
taper  pin  the  right  way. 

No.  3. — To  Remove  Lower  Sprocket  443,  P.  2,  follow  In- 
struction Nos.  1  and  2. 

No.  4. — To  Remove  Gear,  454,  P.  2,  follow  Instruction  Nos. 
1  and  2. 

No.  5— To  Remove  Film  Slide,  A-P  18,  P.  2,  carrying  with 
it  film  cradle  382,  P.  2,  and  film  guiding  spool  536,  P.  2,  fol- 
low Instruction  Nos.  1  and  2,  ana  then  remove  sciew  527, 
P.  2,  at'  the  lower  end  of  the  film  slide,  and  screws  (two  of 


FOR   MANAGERS   AND    OPERATORS 


567 


them)  501,  P.  2,  and  screws  526  (two  'of  them),  P.  2.  The 
dark  metal  part  382,  P.  2,  a  portion  of  which  is  seen  below 
and  a  portion  above  the  aperture,  is  all  in  one  piece  and  is 


Figure  272. 

attached  to  the  nickel  plated  parts  372  (R  and  L),  P.  2,  by 
eight  screws,  the  ends  of  which  can  be  seen  in  nickel  plated 
part. 

No.  6.— Film  Strips,  438,  P.  2  (two  of  them),  ngiu  and 
left,  are  the  strips  upon  which  the  film  slides,  and  which 
receive  the  pressure  of  the  tension  shoes.  These  strips  are 
steel  spring.  Should  they  at  any  time  show  signs  of  wear 
they  may  be  renewed  by  proceeding  as  follows:  Follow 
Instructions  Nos.  1,  2  and  5,  and  then  take  out  the  eight 
screws  which  hold  the  dark  metal  part,  382,  P.  2,  to  the 
nickel  plated  parts,  372  (R  and  L),  P.  2;  slide  out  the  film 
strips  on  that  side  and  put  in  the  new  ones. 


568 


MOTION    PICTURE    HANDBOOK 


Caution:  In  putting  in  new  film  strips  see  to  it  that  the 
nickel  plated  part  clamps  down  tightly,  so  that  there  is  no  crack 
or  space  between  the  two.  If  there  is  it  is  likely  that  the  edge 
of  the  film  will  wedge  in  this  space  and  rip  off  a  portion  of 


538 


—  485-1 

—  507 


525  - 


Plate  1,  Figure  273. 

its  edge.  Where  film  is  injured  in  this  way  by  a  standard 
machine  that  is  the  place  where  the  operator  may  look  for 
the  trouble.  The  process  of  reassembling  the  parts  is  but  a 
reversal  of  their  disassembling. 

No.  7. — To  Remove  the  Film  Guiding  Spool,  536,  P.  2,  fol- 
low Instruction  Nos.  1,  2  and  5,  and  then  drive  out  the  taper 
pin  in  the  steel  collars  in  either  end  of  spool  spindle.  These 
pins  are  taper  and  you  will  need  a  very  fine  punch  to  get 
them  out.  However,  it  is  not  likely  that  this  particular  opera- 
tion will  ever  be  necessary,  as  the  collars  are  casehardened. 

No.  8. — To  Remove  Aperture  Plate,  439,  P.  2,  follow  In- 
struction Nos.  1,  2  and  5.  You  can  then  take  the  plate  loose 
by  removing  two  screws  at  its  top  end. 

No.  9. — To  Remove  Gear,  407,  P.  2,  first  take  off  belt  pulley 


FOR   MANAGERS   AND    OPERATORS 


569 


391,  P.  2  (if  it  is  on  that  shaft;  it  may  be  on  the  transmission 
spindle  377,  P.  4),  and  then  drive  out  the  taper  pin  in  the 
hub  of  gear,  which  releases  the  gear,  though  it  may  be  neces- 
sary to  remove  cap  496-1,  P.  1,  and  tap  gently  on  the  side  of 
the  gear  to  force  it  off,  using  a  soft  punch  of  course. 


442— 


S-A-517 


449 


448 

450 

499 

536-2 


Plate  2,  Pigure  274. 

No.  10.— To  Remove  Fly  Wheel  Shaft,  393,  P.  1,  first  take 
off  the  oil  well  cover  389-1,  P.  3.  Next  loosen  set  screw  392-3, 
P.  6.  This  screw  is  in  the  edge  of  the  cam  opposite  screw  392-2, 
P.  6.  You  will  need  a  small  screwdriver,  as  it  is  countersunk 
into  the  cam.  There  are  two  of  these  screws,  one  on  top  of 
the  other,  the  outer  one  acting  as  a  lock  to  the  inner  one. 
Remove  the  outer  one  and  then  run  your  screwdriver  down 
into  the  hole  and  loosen  the  inner  one.  After  loosening  the 
under  screw,  with  the  screwdriver  still  in  the  hole  to  hold  the 
cam  stationary,  with  the  left  hand  revolve  the  fly  wheel,  at  the 
same  time  pulling  outward  on  the  cam,  and  you  will  thus 
gradually  work  it  off  the  shaft.  Having  done  this,  drive  out 


570 


MOTION    PICTURE   HANDBOOK 


taper  pin  in  the  hub  of  fly  wheel  390,  P.  2,  and  loosen  two 
set  screws  in  collar  409,  P.  2.  You  can  then  pull  the  fly 
wheel  shaft  out  to  the  left. 

No.  11.— To  Remove  Fly  Wheel,  390,  P.  2,  follow  Instruc- 
tion No.  10,  as  it  is  also  necessary  to  remove  its  shaft. 


Plate  3,  Figure  275. 

No.  12.— To  Remove  Intermittent  Sprocket,  399,  P.  2,  take 
off  oil  well  cover,  389-1,  P.  3.  Remove  set  screw,  392-3,  P.  6. 
(See  Instruction  No.  10  for  details  of  removing  cam.)  Hav- 
ing removed  cam  392,  P.  6,  drive  the  taper  pin  out  of  the  hub 
of  intermittent  sprocket  399,  P.  2,  loosen  the  set  screw  in 


FOR    MANAGERS   AND    OPERATORS  571 

collar  395,  P.  2,  whereupon  you  can  pull  star  394,  P.  6,  and 
its  shaft  out  to  the  right. 

Caution. — In  replacing  the  intermittent  sprocket  or  putting 
in  a  new  one  be  sure  to  get  the  felt  washer  between  the 
eccentric  bushing  and  brass  collar,  and  be  sure  to  get  the 
taper  pin  in  hub  of  sprocket  right  end  to.  I  would  strongly 
advise  managers  and  operators  against  attempting  to  fit  a 
new  intermittent  sprocket  to  the  old  shaft.  These  parts  are 
presumed  to  be  standard,  but  the  intermittent  sprocket  and 
star  are  literally  the  heart  of  the  moving  picture  machine,  and 
the  variation  of  only  so  much  as  1/1000  of  an  inch  would  be 
very  perceptible  on  your  screen.  It  would  be  much  better 
and  would  cost  but  a  few  cents  to  send  the  star  and  shaft 
to  the  factory  by  parcel  post  and  have  a  new  sprocket  fitted 
to  the  shaft  when  the  old  one  wears  out.  See  General  In- 
struction No.  8. 

~No.  13.— To  Remove  Eccentric  Bushings  396,  397  and  398, 
or  either  one  of  them,  follow  Instruction  No.  12,  and  then 
loosen  the  screws  'in  caps,  497,  498,  P.  2,  which  will  release 
the  bushing.  It  may  be  necessary  to  tap  the  right  hand  cap 
lightly,  since  it  may  be  stuck  to  the  oil  well  casing  by  shellac 
which  is  used  to  make  the  joint  between  the  frame  and  the 
oil  well  tight.  At  the  right  hand  end  of  intermittent  sprocket 
399,  P.  2,  is  a  brass  collar,  396,  P.  2,  which  rests  snugly 
against  the  end  of  eccentric  bushing  397,  P.  2.  Between 
these  two  is  a  thin  felt  washer.  This  washer  is  for  the 
purpose  of  preventing  oil  from  leaking  out  of  the  oil  well. 
In  replacing  oil  well  cover,  clean  the  edges  thoroughly,  and 
smear  edge  of  cover  with  thick  shellac  (to  be  had  from  any 
painter).  After  clamping  cover  on  let  stand  a  few  hours 
betore  putting  in  oil. 

Caution. — Don't  put  on  too  much  shellac  or  it  will  squeeze 
out  inside  the  well  and  may  break  off  and  injure  the  inter- 
mittent movement,  as  these  small  pieces  are  very  hard. 

No.  14.— Adjusting  the  Intermittent.  See  General  Instruc- 
tion No.  5.  In  order  to  accomplish  this  adjustment  loosen 
cap  screws  509,  P.  2,  and,  using  a  punch  set  in  the  holes  pro- 
vided in  eccentric  bushings  397  and  398,  P.  2,  gently  tap  the 
bushings  in  such  way  that  the  side  toward  you  will  move  in 
an  upward  direction.  Be  very  sure  and  turn  both  these 
bushings  the  same  amount,  since  otherwise  you  will  raise 
one  end  of  the  shaft  more  than  the  other,  thus  not  only 
throwing  the  star  out  of  square  with  the  cam,  but  throwing 
the  work  of  pulling  the  film  down  on  the  teeth  on  one  side  of 


572 


MOTION    PICTURE    HANDBOOK 


the  sprocket,  which  is  very  bad  indeed,  besides  causing  the 
shaft  to  bind  in  the  bushings.  There  is  a  scratch  mark  on  each 
bushing  and  you  must  keep  these  two  scratch  marks  in  exact 
alignment  with  each  other.  In  putting  in  a  new  set  of  bushings 
see  to  it  that  the  thick  part  of  the  bushing  rests  against  the 
cap — is  toward  you — and  that  the  little  holes  drilled  in  the 
circumference  of  the  bushing  near  one  end  comes  next  to  the 
fly  wheel,  and  not  under  the  cap.  This  will  bring  your  bushing 
right. 


-460 


Plate  4,  Figure  276. 

No.  15.— To  Remove  Bushing,  408,  P.  2,  under  cap  496,  P.  1, 
follow  Instruction  No.  9  and  remove  cap  496,  P.  1,  by  taking 
out  the  two  screws  in  its  face.  You  can  then  pull  the  bush- 
ing off  and  put  in  a  new  one. 

No.  16. — The  Framing  Carriage  is  raised  and  lowered  by 
means  of  eccentric  457  and  sliding  box  459,  P.  1.  The  fram- 


FOR    MANAGERS   AND    OPERATORS 


573 


ing  carriage  is  made  to  work  tight  or  loose  by  means  of 
screw  460,  P.  4.  These  parts  may  be  removed  by  first  taking 
off  framing  handle  458,  P.  1,  then  follow  Instruction  No.  23. 
When  you  get  the  front  cover  plate  removed,  i_ull  out  split 
key  530,  P.  5,  and  remove  screw  460,  P.  4,  whereupon  you  can 
pull  out  shaft  456-1,  carrying  the  eccentric,  from  the  front. 
This  will  also  release  sliding  box  459,  P.  1. 

No.  17.— To  Remove  Revolving  Shutter,  A-P  20,  P.  3,  from 
its  shaft  simply  loosen  522,  P.  4,  and  pull  it  off  the  shaft.  To 
remove  the  shutter  and  its  shaft  386-1,  P.  3,  just  pull  outward, 
tapping  gently  with  a  hammer,  if  necessary.  The  shaft  is 
simply  stuck  in  and  fitted  with  a  taper  joint,  there  being  a 
key  and  keyway  to  give  it  the  right  circumferential  location. 


418- 


Plate  5,  Figure  277. 

No.  18.— To  Remove  the  Shutter  Blade  376,  P.  3,  and  sub- 
stitute another  of  different  form,  remove  the  six  screws  in 
outer  rim  479,  P.  3;  take  off  the  old  blade  and  put  on  the 
new  one,  replacing  the  screws. 


574  MOTION    PICTURE   HANDBOOK 

No.  19.— To  Remove  the  Yoke  Holder,  378,  P.  4,  take  out 
screws  500,  P.  4,  and  pull  the  casting  off.  In  replacing  this 
yoke  be  sure  that  the  bearing  surfaces  are  perfectly  clean. 

No.  20.— To  Remove  Yoke  467,  P.  4,  follow  Instruction 
No.  20  and  take  out  screw  503,  P.  4. 

No.  21. — To  Remove  the  Casting,  386,  P.  4,  carrying  the  re- 
volving shutter  shaft,  vertical  shaft  468  and  horizontal  shaft 
386-2,  P.  4,  first  follow  Instruction  No.  20*and  then  remove 
screws  (two  of  them)  528,  P.  4.  This  releases  the  casting 
carrying  the  three  shafts  named,  and  the  five  gears  mounted 
thereon. 

Caution:  In  replacing  this  casting  be  sure  that  you  get 
the  washers  just  as  they  were,  because  there  is  likely  to  be 
a  variation  in  the  thickness  of  the  two  washers  and  if  you 
get  them  switched  you  will  have  trouble  with  the  gears 
binding. 

The  number  of  the  casting  with  its  assembled  parts  is 
A-P-10,  including  the  three  shafts  named,  and  gears  475 
(three  of  them),  gear  474,  and  sliding  gear  472,  all  on  P.  4. 

/  would  not  advise  the  operator,  to  attempt  to  replace  any  of 
these  parts.  If  it  becomes  necessary  to  do  anything  to  them, 
take  the  whole  part  off  and  send  it  to  the  factory  by  insured 
parcel  post. 

No.  22. — To  Remove  Front  Plate  Cover,  529,  P.  4,  first 
follow  Instructions  Nos.  19  and  21.  Then  take  out  seven 
small  flat  head  screws  on  face  of  the  cover,  which  releases  the 
whole  thing. 

No.  23.— To  Remove  Crank  Shaft,  385,  P.  5,  drive  taper 
pin  out  of  part  418,  P.  5,  follow  Instruction  No.  22,  and  then 
drive  out  the  taper  pin  in  fhe  collar  next  the  left  side  of  the 
mechanism  casting  .and  the  taper  pin  in  .the  hub  of  gear 
S-A  417,  P.  5.  This  releases  the  shaft,  which  may  be  pulled 
out  to  the  right  as  you  face  the  lens  end  of  the  machine. 

No.  24. — To  Remove  Transmission  Spindle,  377,  P.  5,  fol 
low  Instruction  No.  23.  Drive  the  taper  pin  out  of  gear  421 
and  422,  P.  5.  Drive  the  taper  pin  out  of  the  hub  of  gear 
423,  P.  4,  which  releases  the  shaft,  and  allows  it  to  be  driven 
out  to  the  right  as  you  face  the  lens  end  of  the  machine. 

No.  25.— To  Remove  the  Governor  Lever,  A-P  13,  P.  2, 
it  is  only  necessary  to  lower  the  framing  carriage,  stick  a 
screwdriver  from  the  right  hand  side  and  remove  screw  511, 
P.  5. 

No.  26.— To  Remove  Plate  Covering  the  Top  of  the  Ma- 


FOR    MANAGERS   AND    OPERATORS  575 

chine,  513,  P.  5,  take  out  five  flat  head  screws  on  the  top  of 
the  plate  and  one  on  the  lip  which  comes  down  in  front. 

No.  27.— To  Remove  Governor  Vertical  Shaft,  427,  P.  5, 
follow  Instructions  Nos.  22  and  26,  then  drive  out  the  taper 
pin  in  the  hub  of  gear  434  and  taper  pin  in  collar  433.  Drive 
out  the  straight  pin  432,  in  the  top  of  the  governor  weights 
430,  and  the  stop  pin  in  the  shaft  just  above  the  sliding 
collar,  all  in  Plate  5.  This  will  release  the  shaft,  which  can 
be  lifted  or  driven  out  upward.  This  instruction  applies 
equally  to  the  removal  of  any  one  of  the  parts  mounted  on 
spindle  427,  except  the  lower  gear,  which  may  be  removed 
by  merely  following  Instruction  No.  23  and  driving  out  the 
taper  pin  in  its  hub. 

No.  28.^To  Remove  the  Upper  Sprocket,  443,  P.  3,  drive 
out  the  taper  pin  in  its  hub  and  pull  sprocket  off  its  shaft. 
The  shaft  may  also  be  removed  by  driving  out  taper  pin  in 
gear  444,  P.  2,  having  first  removed  the  sprocket,  of  course. 

No.  29.— To  Remove  Upper  Sprocket  Idler  Shaft,  447,  P.  2, 
take  out  the  screw  holding  lever  446,  P.  4,  and  slide  the 
shaft  out  to  the  right. 

No.  30.— Adjusting  Sprocket  Idlers.  The  distance  of  the 
two  intermittent  sprocket  idlers  488,  P.  3,  from  the  sprocket 
is  governed  by  screw  537,  P.  1.  When  making  this  adjust- 
ment be  sure  that  you  set  the  lock  nut  on  screw  up  tight. 
Part  485,  P.  1,  contains  the  two  lower  sprocket  idler  rolle:s 
539,  P.  4.  The  distance  of  these  rollers  from  the  sprocket  is 
governed  by  screws  538.  These  idlers  should  be  set  as  per 
General  Instruction  No.  12. 

No.  31. — Tension.  (See  General  Instruction  No.  9).  The 
tension  may  be  altered  by  tightening  or  loosening  screws 
(six  of  them)  494,  P.  1. 

No.  32. — Tension  Shoes,  374,  P.  4,  may  be  removed  by 
driving  out  the  small  taper  pin  in  their  lower  end,  and 
sliding  the  shoes  out. 

No.  33.— Tension  is  supplied  to  the  take-up  as  follows: 
Part  S-A  388,  P.  2,  is  attached  rigidly  to  shaft  385,  P.  5.  Chain 
sprocket  wheel  S-A  415  is  mounted  loosely  on  the  same  shaft 
with  a  cotton  belting  washer,  415-7,  P.  1,  between  the  two. 
These  three  parts  are  held  together  under  pressure  by 
springs,  387-1,  P.  1,  the  tension  of  which  is  governed  by 
thumbscrew,  385-1,  this  thumbscrew  being  locked  in  place  on 
the  shaft  by  screw  387-2.  Setting  this  thumb  screw  inward, 
thus  giving  the  springs  more  compression,  has  the  effect  of 


576 


MOTION   PICTURE   HANDBOOK 


increasing  the  pull  on  the  take-up  reel,  and  loosening  it  has 
the  opposite  effect. 

Caution:  It  is  necessary  that  washer  415-7,  P.  1,  be  kept 
clean  and  dry.  Don't  allow  oil  from  the  chain  to  get  on  it 
or  you  will  have  trouble.  To  move  screw  385-1  slack  off  on 
the  screws  on  its  face. 


392 


392-2 


389 
39$ 


Plate  6,  Figure  278. 

No.  34. — Oil.     (See   General  Instruction  No.  1.) 
No.  35. — Setting  Shutter.    (See  General  Instruction  No.  18.) 
No.  36. — Adjusting  Intermittent.    (See  General  Instruction 
No.  5.) 
No.  37.— Clean  Sprockets.   (See  General  Instruction  No.  3.) 


FOR    MANAGERS   AND    OPERATORS 


577 


NAMES  AND  NUMBERS   OF  PARTS   FOR  THE 
STANDARD  MECHANISM,  MASTER  MODEL 

Order    Parts    by    Number    Only.      These    Numbers   Are   the 

Manufacturer's      Regular      Stock      Numbers.        The 

First  Column  of  Figures  Indicates  'the  Plate 

on  Which   the  Part  is  Shown. 


Plate  Part 
No.       No. 
2         —372 


—373 
— 374 


— 375 


3  —376 
5  &  4—377 

4  —378 
4         —379 
3        —381 


—382 

—383 

—385 

—385-1 

— 386 

—386-1 

— <386-2 


—  387-1 
—387-2 
—388* 
—389 

—  389-1 
—389-3 
—389-4 
—390 
—391 

6        —392 
6        —392-1 


—392-2 
—  392-3 


6  &  1—393 
6  —394 
2  —395 
2  —396 
2  —397 
6  &  2—398 

2  —  399 
2  —407 
2  —408 


—409 
—414-1 
— 415-7 
—415* 


Name. 
Sides    for   film    slide, 

R.    &   L. 
Gate  blank. 
Long    tension    strips, 

R.    &   L. 
Short   tension   strips, 

R.    &    L. 

Outside  shutter  blade. 
Transmission  spindle. 
Yoke  holder. 
Gate  hinge,  R.   &  L. 
Guide    for    threading 

machine. 
Film    cradle. 
Oil    guard. 
Driving  spindle. 
Split   nut. 
Shutter  casting. 
Shutter    shaft. 
Horizontal        shutter 

Bhaft. 

Spring  for  takeup. 
Screw  for  split  nut. 
Friction  washer. 
Inside   oil   box. 
Outside    oil    box. 
Oiler  for  oil  box. 
Screws    (4). 
Balance  wheel. 
Motor  pulley. 
Cam. 
Cam    wheel     driving 

pin. 
Set     screw     to     hold 

pin. 
Set    screws    to    hold 

cam  to  shaft   (2). 
Cam    shaft. 
Star. 

Set   collar. 
Nut  for   397. 
Bushing  for  394  long. 
Bushing        for        394 

short. 

Intermittent  sprocket 
Gear — 14    teeth. 
Bronze  bearing   (un- 
der cap  496). 
Collar. 
Collar. 

Friction  washer. 
20-tooth  chain 

sprocket    complete. 


Plate  Part 
No.      No. 
—417* 
—418 
— 419-1 
—419-2 
—419-3 
—  24t 
—421 
—422 
— 1423 
—424 
—425 
—426 


—427 
—428 

—429 
—431 
— 430-1 
— 431 
—432 
—433 

—  13t 

—434 
—435 
— 435-2 

— 435-4 
— 436 
—436-1 

—  18t 


2  —439 
2  —  17t 
2  —442 

2  &3— 443 


2 

4  — 446 

2  —447 

2  — 448 

2  — 448-1- 

2  —449 


Name. 

70-tooth   gear. 

Clutch  collar. 

Wooden   handle. 

Guide   bushing. 

Handle  screw. 

Crank   complete. 

Gear — 15  teeth. 

Gear — 12  teeth. 

Gear — 42  teeth. 

Stereo  bracket. 

Stereo  extension  bar. 

Stereo  single  glass 
casting. 

Governor  spindle. 

Sliding  gear  on  gov- 
ernor. 

Governor    head. 

Governor  wings. 

Screws     (4). 

Governor  arms. 

Governor   pin. 

Governor  collar. 

Governor  lever  com- 
plete. 

Gear— 8    teeth. 

Fire  shutter. 

Fire  shutter  catch 
blank — R.  &  L,. 

Screws  for  436    (4). 

Gate  latch  slide. 

Gate   latch. 

Film   slid*    complete. 

Right  and  left  film 
strips. 

Aperture  plate. 

Film  chute  complete. 

Upper  sprocket  spin- 
dle. 

Upper  and  lower 
sprocket. 

Gear — 20    teeth. 

Upper  sprocket  idler 
roller  lever. 

Upper  sprocket  idler 
roller  spindle. 

Upper  sprocket  idler 
roller  bracket 
(left). 

Upper  Idler  adjust- 
ment screw. 

Upper  sprocket  Idler 
roller  bracket 
(right). 


578 


MOTION   PICTURE   HANDBOOK 


Plate  Part 
No.      No. 


— 450 
—  16t 

— 452 

—454 
—455 
—456-1 

— 457 
— 458 
—459 
— 460 

— 461 
— 462 
—465 

— 466* 


3 

—466-1 

4 

—467 

4 
4 

—  468 
—  471 

4 

—472 

4 

—  474 

4 

—475 

4 

—  476 

4 

—477 

4 

—  478 

3 

—479 

4 

—480 

—  20t 

—  lot 

4 

—481 

3 

—  483 

4 
4 

1 
3 

—484-1 
—  485 
&  4—485-1 
—  487* 

3 

—  487-2 

3 

—  488 

1 

—  491 

Name. 

Upper  idler   rollers. 
Upper     idler     com- 
plete. 

Lower  sprocket  spin- 
dle. 

Gear — 16   teeth. 

Collar. 

Framing  device  spin- 
dle. 

Framing1    device    ec- 
centric. 

Framing  device  han- 
dle. 

Framing  device  slid- 
ing box. 

Adjustment  screw  for 
sliding  box. 

Large    frame. 

Sliding  frame. 

Shoe  to  fasten  lower 
magazine  to  head. 

Knee    and    stud    as- 
sembled. 

Knee    to   fasten   arm 
for  take-up. 

Yoke       for       outside 
shutter. 

Vertical  shaft  in  386. 

Bronze     bearing     for 
outside  shutter. 

Sliding  gear  for  out- 
side shutter. 

Vertical      g  e  a  r — 12 
teeth. 

Gear — 12    teeth,   out- 
side sihutter   (3). 

Bronze  bushing,  out- 
side   shutter. 

Bronze   ring,    outside 
shutter. 

Aluminum  flange  for 
outside  shutter. 

Aluminum     ring    for 
outside  shutter. 

Key  for  outside  shut- 
ter. 

Outside  shutter  com- 
plete. 

Outside  shutter  cast- 
ing  complete. 

Key  for  sliding  gear 
472. 

Stud     for     telescope 
leg. 

Screws    (7). 

Complete   roller  box. 

Roller   box   casting. 

Idler       bracket       on 
gate,   assembled. 

Idler       bracket       on 
gate. 

Rollers        on        Idler 
bracket. 

Cup        for        tension 
spring  on  gate  (6). 


Plate  Part 
No.      No. 
1        — 493 


—494 
—495 

—496 
— 496-1 
—497 

— 498 
—499 

—500 
—501 


1        —502 
1  &  4 — 503 


—504 

—504-1 

—505 

— 506 
— 507 

— 509 
—511 

—512 
—514 
—513 
— J513-1 
—  22t 
— 515 

—516 

—518 
—517* 

—521 
—521 
—522 


—523 
—525 


2         —526 
1  &  2—527 


4         —528 


4         — 529 
4         —529-1 


Name. 

Tension  stud  inside 
of  491  (6). 

Tension  nut  Inside  of 
491  (6). 

Tension  spring  in- 
side of  491  (6). 

Cap  for  cam  spindle. 

Screws  for  496    (2). 

Cap  for  intermittent 
movement. 

Cap  for  intermittent 
movement. 

Spring  for  guiding 
spool. 

Screws  for  378    (2). 

Screws  for  gate 
latch  (2). 

Spring  on  gate  latch. 

Screws  for  sliding 
rods  (4). 

Sliding  rod — short. 

Sliding    rod — long. 

Thumb  screw  for 
424. 

Spindle  holding  gate. 

Screw  for  framing 
handle. 

Screws  for  497  and 
498  (4). 

Screw  for  governor 
lever. 

Light   shield. 

Top    rollers     (2). 

Top   plate. 

Flap  for  top   plate. 

Top  plate  complete. 

Bracket  for  rollers 
in  top  plate  (2). 

Screws  to  hold  light 
shield  (2). 

Screws    (5). 

Catch  for  fire  shut- 
ter assembled. 

Thumb  screw  hold- 
ing stereo  bracket. 

Thumb  screw  hold- 
ing magazines  (4). 

Screw  holding  out- 
side shutter  to 
shaft. 

Screw    holding    471. 

Screw  for  holding 
gate  spindle. 

Screws  for  holding 
film  slide  (2). 

Screw  for  holding 
film  slide  and 
screw  for  534  and 
502  (3). 

Screws  to  hold  out- 
side shutter  cast- 
ing (2). 

Front  plate. 

Lens    ring. 


FOR    MANAGERS   AND    OPERATORS 


579 


Plate  Part 

Plate  Part 

No. 

No. 

Name. 

No. 

No. 

Name. 

5 

—  530 

Cotter  pin  for  fram- 

— 503 

Screw    to    hold    yok« 

ing  device  spindle. 

holder    to    shutter 

3 

—  531 

Screws  to  fasten   465 

casting. 

to   461    (2). 

2 

—536-3 

Guiding    spool    spin- 

— 532 

Small     set    screw    in 

dle. 

handle. 

1 

—  537 

Set   screw   and   nut. 

1 

—  534 

Tension      spring     for 

1 

—  538 

Set  screw  and  nut. 

idler   bracket. 

4 

—539 

Rollers        in        roller 

1 

—535 

Pin  for  idler  bracket. 

box    485. 

o 

—  536 

Guiding     spool     film 

3 

—  540 

Upper  idler  spring. 

slide  —  short. 

3  & 

4—  20t 

Outside  shutter  com- 

2 

—  536-1 

Guiding     spool     flkn 

plete. 

slide  —  long. 

3 

—  24f 

Crank   complete. 

2 

—536-2 

Space     bushing     for 

—     0 

Oil    holes. 

spool. 

•S.     A. 

tA.     P. 

Edison  Kinetoscope 

Instructions  for  Model  D 

No.  1. — To  Remove  Framing  Lever,  18047,  P.  2,  unscrew 
from  head  of  the  adjusting  gear  shaft. 

No.  2.— Driving  Crank,  18066,  P.  1,  is  secured  to  the  shaft 
by  means  of  a  spring  catch.  It  is  released  merely  by  press- 
ing on  the  spring  and  pulling  outward. 

No.  3.— To  Remove  Adjusting  Gear  Shaft,  18052,  P.  1,  and 
brackets  18057  and  18058,  P.  1,  remove  screws  (four  of  them) 
17585,  P.  1.  The  removal  of  these  screws  releases  both 
brackets  and  the  shaft.  If  it  is  desired  still  to  further  dis- 
semble the  parts,  loosen  collar  set  screws  2798,  P.  1,  where- 
upon you  can  pull  the  right  hand  bracket  off  the  shaft 
together  with  collar  18055,  P.  1.  If  it  is  desired  also  to 
remove  the  left  hand  bracket,  18058,  P.  1,  drive  out  pin  in 
the  hub  of  adjusting  gear,  18049,  P.  2,  slip  the  gear  off  the 
shaft,  and  this  releases  the  bracket. 

No.  4. — To  Remove  the  Gate,  together  witfr  parts  assembled 
thereon,  pull  out  hinge  rod,  18193,  P.  2.  If  the  hinge  pin  or 
gate  sticks  tap  gently  until  released. 

No.  5. — To  Remove  Aperture  Plate,  19334,  P.  1,  remove 
screw  19346,  P.  3,  and  another  similar  screw  immediately 
opposite,  which  releases  part  19320,  P.  1.  Next  remove  screws 
20242,  P.  1,  pulling  framing  lever  18047,  P.  2,  down  as  far  as 
it  will  go,  in  or,der  to  disclose  the  upper  one  of  the  screws. 
The  removal  of  the  four  named  screws  releases  the  aperture 
plate,  carrying  with  it  part  19319  and  film  tracks  19318  and 
19317  and  guide  rollers  19339,  all  shown  on  P.  1.  The  re- 
placement of  these  parts  is  merely  a  reversal  of  the  process 


580 


MOTION    PICTURE    HANDBOOK 


of  their  dissembling,  but  be  sure  you  set  screws  20242,  P.  1,  in 
snugly,  and  that  there  is  no  dirt  between  the  faces  of  the  parts, 
as  these  screws  support  the  aperture  plate. 


Figure  279. 


In  this  connection  let  it  be  noted  that  the  aperture  is  sup- 
ported by  a  casting  having  its  base  just  back  of  arrow  head 
38,  P.  2.  Should  your  aperture  at  any  time  get  out  of  line 


FOR    MANAGERS   AND    OPERATORS  581 

the  first  thing  to  do  is   make  sure  the  screws  holding   this 
casting  have  not  become  loosened. 

No.  6.— To  Remove  Film  Guide  Rollers,  19339,  P.  1,  follow 
Instruction  No.  5  and  then  pull  out  the  split  key  at  the  end 
of  the  spindle,  which  will  release  the  parts.  You  cannot  get 
the  guide  roller  spindle  out  until  you  have  released  part 
19320,  P.  1,  as  per  Instruction  No.  5. 

No.  7.— Film  Tracks,  19317  and  19318,  P.  1,  are  of  spring 
steel,  and  are  removable.  When  in  the  course  of  time  they 
become  worn  it  is  only  necessary  to  order  new  parts  (they 
are  right  and  left  hand,  as  per  numbers  given  on  P.  1,  there- 
fore order  the  one  you  want  by  number}.  Remove  screws 
(six  of  them)  19344,  P.  1,  lift  off  parts  19320  and  19319,  P.  1, 
take  out  the  old  tracks  and  put  in  the  new.  They  are  notched 
to  fit  the  screws,  hence  you  cannot  get  them  wrong,  even  if 
you  try.  Be  careful  and  don't  drop  the  small  screws.  A 
magnetized  screwdriver  is  an  excellent  tool  with  which  to 
handle  small  parts.  See  General  Instruction  No.  19. 

No.  8.— To  Remove  Part  19325,  P.  1,  follow  Instruction 
No.  5. 

No.  9.— To  Remove  Upper  Film  Guide,  19321,  P.  2,  take  out 
two  screws,  20636,  P.  2. 

No.  10.— Gate  Latch,  18758,  P.  3,  may  be  removed  by  taking 
out  screws  18207  and  20406,  P.  3.  Screws  18207  and  18207  (one 
at  the  top  and  one  at  the  bottom)  serve  to  regulate  the  dis- 
tance of  the  gate  from  the  machine  casting.  They  should  be 
so  set  that  the  distance  between  the  machine  casting  and  the 
gate  casting  is  the  same  at  both  sides  of  the  gate.  Unless 
the  gate  sets  thus  the  tension  shoes  will  exert  unequal  pres- 
sure on  the  film.  Should  it  ever  be  necessary  to  move  these 
screws  be  sure  their  lock  nut  is  set  up  tightly  when' you  have 
finished.  If  at  any  time  the  gate  latch  should  fail  to  work 
right  it  is  possible  the  small  coil  spring  behind  it  has  become 
too  weak  and  needs  stretching.  This  can  easily  be  accom- 
plished by  removing  the  gate  latch. 

No.  11.— The  Automatic  Fire  Shutter  Governor  may  be 
removed  by  loosening  screw  18779,  P.  3,  which  is  the  small 
set  screw  in  collar  18778,  P.  3,  on  the  outer  end  of  its  spindle, 
and  set  screw  8132,  P.  3.  Having  done  this  you  may  slip 
spindle  19331,  P.  3,  carrying  gear  on  its  inner  end  out,  which 
releases  the  fire  shutter.  The  hub,  which  set  screw  8132 
holds  to  the  shaft,  and  which  contains  screws  (two  of  them) 
18795,  P.  3,  is  a  part  of  the  clutch  disc  which  holds  the 
governor  weights.  The  governor  cover,  18791,  P.  3,  may  be 


582 


MOTION    PICTURE    HANDBOOK 


removed  (having  first  followed  the  first  part  of  this  instruc- 
tion) by  taking  out  screws  8141  (two  of  them),  P.  3.  Having 
removed  the  governor  from  the  gate  you  will  see  on  the 
inner  end  of  the  hub  in  which  was  shaft  19331,  P.  3,  a  brass 


2076 
17585 
2798 


18058 


18117 


Plate  1,  Figure  280. 

collar.  This  collar  is  merely  pressed  on  the  hub,  and  is  held 
there  by  friction  alone.  It  may  be  pried  off  with  a  knife  blade, 
or  be  removed  with  a  pair  of  gas  pliers.  Having  removed  this 
collar,  which  is  part  18785,  you  can  lift  off  the  shutter  blade  and 


FOR    MANAGERS   AND    OPERATORS  583 

weight,  thus  revealing  a  spider-shaped  copper  spring.  This  spring 
is  for  the  purpose  of  holding  the  shutter  blade  away  from 
the  revolving  mechanism  after  the  shutter  is  locked  open, 
thus  eliminating  considerable  friction  which  otherwise  would 
be  present.  It  will  be  noted  that  three  of  the  prongs  of  the 
spring  are  bent  upward  and  three  are  flattened  out  against 
th-e  metal.  This  is  as  it  should  be,  since  the  spring  must 
provide  friction  between  the  revolving  part  and  the  shutter 
blade  until  the  shutter  blade  has  been  raised.  Do  not  bend 
the  prongs,  but  leave  them  as  you  find  them.  This  spring 
should  be  examined  once  in  a  while,  since  it  will  naturally 
develop  some  wear,  which  has  the  effect  of  allowing  the 
metal  revolving  part  to  rub  too  hard  against  the  shutter 
blade,  thus  causing  undue  friction.  The  governor  may  be 
still  further  dissembled  by  removing  screws,  (two  of  them) 

18795,  P.  3,  which  are  in  the  head  of  the  nickel-plated  hub 
of  the  clutch  disc.     These  two  screws  have  on  their  circum- 
ference  small   spiral   springs,   the   part   number   of  which    is 

18796.  Be  careful  and   do   not  lose   these   springs.     Their   use 
and  purpose  is  as  follows:     When  the  semi-circular  weights, 
which  you  will  see  when  cover  18791,  P.  3,  is  removed,  spread 
open  through  centrifugal  force,  the  part  carrying  the  shutter 
blade  is  forced  outward,  toward  the  gate,  against  the  pres- 
sure of  these  springs,   by  the   two  little  arms  or  levers  on 
their   inner   ends.     This   has   the    effect    of   locking   the   fire 
shutter  open  when  the  machine  has  attained  speed,  so  that 
all  friction  is   removed.     When   the   speed  drops  below  the 
danger  point,  these  leaden  weights  fall  inward,  and  the  two 
little  springs  pull  the  central  metal  part,  carrying  the  shutter 
blade  inward  again,  thus  unlocking  the  shutter  blade  and  allow- 
ing it  to  fall  and  shut  off  the  light  from  the  film. 

No.  12. — Bracket,  18780,  P.  3,  which  supports  outer  end  of 
governor  spindle  19331,  P.  3,  is  held  by  one  screw  and  two  dowel 
pins.  Should  you  have  occasion  to  remove  the  bracket  be 
careful  you  don't  bend  the  pins,  or  you  will  have  trouble. 
Leave  that  particular  bracket  alone,  is  my  advice. 

No.  13.— Tension  Shoes,  19324,  P.  2,  may  be  removed  by 
taking  out  screws  19256,  P.  3.  These  shoes  are  held  against 
the  film  by  two  springs.  These  springs  are  held  in  place  by 
screw  19498,  P.  3,  which  also  serve  to  provide  greater  or  less 
tension.  In  other  words  they  are  the  tension  adjustment 
screws.  By  driving  them  inward  the  film  tension  is  increased, 
and  vice  versa. 

No.  14.— Gate  Idler  Roller,  17950,  P.  2  (end),  and  17949 
(body),  P.  2,  may  be  removed  by  loosening  the  set  screw  in 


584  MOTION    PICTURE   HANDBOOK 

17949,  P.  2.  Gate  idler  roller  bracket,  18766,  P.  2,  and  the 
spring  which  supplies  tension  to  the  bracket,  may  be  removed 
by  driving  out  shaft  which  holds  it.  To  replace  the  spring 
which  this  shaft  carries,  place  the  spring  in  a  straddling  posi- 
tion over  the  center  part  of  the  roller  bracket,  with  the  two 
ends  of  the  spring  at  the  bottom,  and  the  loop-shaped  part 
on  top.  Place  the  spring  in  the  groove  in  the  casting  and 
press  the  bracket  and  spring  down  simultaneously,  pushing 
the  shaft  through  the  bracket  and  spring  and  into  its  bear- 
ing at  the  other  end,  while  holding  the  spring  and  bracket 
down  with  the  other  hand. 

In  case  the  spring  does  not  exert  sufficient  pressure,  grasp 
the  loop  at  the  top  with  a  pair  of  pliers  and  pull  it  outward. 
This  will  have  the  effect  of  making  the  spring  stronger  in  its 
action.  See  to  it  that  the  coils  of  the  spring  are  close  to  the 
central  portion  of  the  bracket. 

No.  15. — The  Shield  covering  the  gears,  P.  2,  is  removed 
by  taking  out  screws  16580  and  16576,  P.  2.  In  replacing  the 
shield,  take  notice  that  there  are  two  washers  on  the  inside  of 
the  shield,  and  two  on  the  outside,  through  which  the  screws 
pass.  Be  sure  and  get  these  washers  in  place  or  things 
won't  "fit  right." 

No.  16.— Bracket;  18108,  P.  1,  carrying  upper  sprocket, 
17992,  P.  3,  and  its  shaft  and  gear,  16594  and  18106,  P.  1,  may 
be  removed  from  the  machine  by  following  Instruction  No. 
15,  and  then  removing  screws  (two  of  them),  2076,  P.  1. 

No.  17.— Upper  Sprocket,  17992,  P.  3,  may  be  removed  from 
its  shaft  merely  by  loosening  a  set  screw  in  its  face.  There 
is  a  set  collar  at  the  right  hand  inner  end  of  the  sprocket, 
designed  to  prevent  end  motion  in  the  shaft  and  hold  the 
sprocket  in  line  with  the  film.  Keep  this  collar  set  up  against 
the  casting  snugly,  but  not  tight  enough  to  bind.  You  may 
remove  top  sprocket  shaft  18106,  P.  1,  and  gear  16594,  P.  1, 
by  loosening  the  set  screw  in  the  before-mentioned  collar  and 
the  one  in  the  hub  of  the  sprocket,  first  having  followed 
Instruction  No.  15. 

No.  18. — Main  Driving  Gear,  16569,  P.  1,  may  be  removed  by 
following  Instruction  No.  2  and  then  removing  screw  and 
v/asher  17804  and  18079,  P.  2. 

No.  19. — Bridge  Casting,  16582,  P.  1,  carrying  gears  16575, 
16574  and  16569,  P.  1,  may  be  removed  by  following  Instruc- 
tion No.  15,  pulling  off  gears  16577  and  16575,  P.  1;  next  re- 
moving screws  (two  of  them,  one  at  either  end  of  the  casting) 
1133,  P.  1,  and  carefully  prying  casting  16582  away. 


FOR    MANAGERS    AND    OPERATORS 


585 


No.  20. — Gear,  19574,  P.  1,  is  removed  by  following  Instruc- 
tions Nos.  15  and  19,  removing  the  screw  in  the  end  of  the 


18302 
19159 


16545 


Plate  2,  Figure  281. 

gear  hub  and  driving  the  shaft  out.     The  shaft  is  attached 
to  gear  19439,  P.  1. 
No.  21.— To  Remove  Fly  Wheel  Shaft,  18684,  P.  1,  follow 


586  MOTION    PICTURE    HANDBOOK 

Instructions  15  and  19,  then  carefully,  using  a  small  steel 
punch,  drive  out  the  pin  in  cam  18138,  P.  1,  and  in  the  hub  of 
bevel  gear  19483,  P.  1.  This  releases  the  shaft  and  flywheel, 
which  then  may  be  pulled  out  to  the  right.  The  process  of 
assembling  is  reversal  of  dissembling. 

tic.  22.— Right  Hand  Fly  Wheel  Shaft  Bushing  may  be  re- 
newed by  following  Instructions  No.  15  and  18,  loosening 
set  screw  18141,  P.  1,  and  taking  out  the  big,  flat  head  screw 
which  holds  the  bushing  in  place.  The  bushing  may  then  be 
pulled  out  and  a  new  one  inserted  in  its  place. 

No.  23. — Left  Hand  Fly  Wheel  Shaft  Bushing  may  be  re- 
newed by  taking  out  the  flat  head  screw  which  holds  it  and 
loosening  set  screw  18141,  P.  1.  The  bushing  may  then  be 
pulled  out  and  a  new  one  inserted. 

No.  24.— Bevel  Gear,  19483,  P.  1,  may  be  removed  by  first 

taking1  out  the  fly  wheel  and  shaft  (see  Instruction  No.  21). 
The  gear  may  then  be  pulled  off  after  driving  out  the  pin  in 
its  hub. 

No.  25. — Cam,  18138,  P.  1,  is  removed  by  following  Instruc- 
tion No.  24  and  then  driving  out  the  pin  in  its  hub.  It  may 
then  be  slipped  off  its  shaft. 

No.  26.— -The  Lower  Film  Guard,  18709,  P.  1,  which  comes 
up  around  the  hub  of  intermittent  sprocket  18702,  P.  1,  may  be 
taken  off  by  removing  two  screws  at  its  lower  end. 

No.  27. — Intermittent  Sprocket  Shaft,  18113,  P.  1,  carrying 
the  intermittent  sprocket  and  star,  may  be  removed  by  following 
Instruction  No.  21,  then  loosening  set  screw,  18141,  P.  1,  and 
slipping  out  the  left  hand  bushing.  You  can  then  take  out 
the  parts. 

No.  28. — Renewing  Intermittent  Sprocket.  /  advise  that  this 
be  not  attempted  by  the  operator.  It  is  far  better,  from  any 
and  every  point  of  view,  to  buy  the  star,  sprocket  and  shaft 
assembled  and  ready  to  put  in.  In  fact  the  owner  will  do 
well  to  have  a  spare  star,  sprocket  and  shaft  assembled  on 
hand,  ready  to  put  into  his  mechanism.  See  General  In- 
struction No.  5. 

No.  29. — Adjusting  Intermittent  Movement.  Star  18111  and 
cam  18138,  P.  1,  will  gradually  develop  lost  motion,  due  to 
wear  in  the  parts  and  in  the  bushings  which  carry  their  shafts. 
The  lost  motion  thus  produced  may  be  eliminated  by  loosen- 
ing set  screw  18141,  P.  1,  and  its  mate  which  holds  the  bush- 
ing in  the  opposite  end  (also  18141,  P.  1),  and  slightly 
revolving  the  bushings,  one  to  the  right  and  one  to  the  left. 


FOR    MANAGERS    AND    OPERATORS 


587 


These    bushings    are    eccentric,    and    this    has    the    effect    of 
raising  or  lowering  die  shaft,  according  to  which  way  you  turn 
the  bushings. 


18039 


18042 


\79QZ 

18118 
132. 
I82Q7 

2T8E 

.18498 

18758 

2Q4Q6 

19256 

1878O 

18156 

182D7 

2782 


Plate  3,  Figure  282. 

Caution:  Don't  turn  your  screwdriver  to  the  right  (clock- 
wise) with  both  bushings.  If  you  do  you  will  raise  one  end  of 
the  shaft  and  lower  the  other.  A  moment's  consideration 
will  show  you  the  rekson  for  this.  The  sprocket  and  star 
should  be  set  just  so  you  can  feel  the  least  bit  of  play  in  the 
intermittent  sprocket.  See  General  Instruction  No.  13. 


588  MOTION    PICTURE   HANDBOOK 

No.  30. — Lower  Roller  Bracket,  19306,  P.  1,  is  removed  by 
loosening  screw  2794,  P.  1.  In  putting  the  bracket  back  insert 
the  shaft  in  the  hole,  and  let  the  bracket  lie  on  the  sprocket 
as  you  tighten  up  screw  2794,  tight.  If  at  any  time  the  tension 
on  this  bracket  is  not  sufficient  it  is  likely  this  screw  has 
loosened  and  is  allowing  the  shaft  to  revolve  somewhat. 
Remedy:  Tighten  the  screw. 

No.  31.— Lower  Roller  Idler,  17949,  P.  1  (body),  and  17950, 
P.  1  (end),  may  be  removed  by  loosening  the  tiny  set  screw 
in  center  of  17949  and  slipping  the  shaft  out. 

No.  32.— Lower  Sprocket  Shaft,  16589,  P.  1,  may  be  slipped 
out  to  the  right  after  you  have  followed  Instruction  No.  15, 
loosened  set  screws  in  the  hub  of  lower  sprocket  and  in  the 
hub  of  chain  sprocket  16814,  P.  3.  In  replacing,  slip  the  shaft 
in  with  the  sprocket  loose,  and  center  it  by  closing  idler  roller 
bracket  19306,  P.  1,  so  that  roller,  17949,  P.  1,  fits  between 
the  flanges  of  the  sprocket.  Tighten  up  the  set  screw  in  the 
hub  of  the  sprocket,  with  the  sprocket  in  this  position,  and 
you  will  be  all  right. 

No.  33. — Casting,  18611,  P.  1,  carrying  lower  sprocket  shaft 
16589,  P.  1,  the  lower  sprocket  and  its  driving  gear,  together 
with  chain  gear  16814,  P.  3,  may  be  removed  in  its  entirety 
by  taking  out  screws  17587  (two  of  them),  P.  1. 

No.  34.— Revolving  Shutter  Shaft,  16593,  P.  3,  and  gear, 
16585,  P.  1,  may  be  removed  by  following  Instruction  No.  26 
and  loosening  set  screws  82,  P.  3,  in  the  holding  collar,  first 
having  removed  the  revolving  shutter.  This  will  allow  you 
to  slip  the  shaft  and  gear  out. 

No.  35.— To  Remove  Gear,  19333,  P.  1,  and  its  shaft,  pro- 
ceed as  follows:  Follow  Instruction  No.  5,  next  follow  In- 
struction No.  15,  and  No.  19  and  No.  21. 

No.  36. — To  Remove  Gear,  19333,  P.  1,  remove  the  two 
screws  in  the  hub  of  gear  16588,  P.  3.  These  screws  are  on 
the  back  end  of  the  hub.  Next  pry  off  gear  16588,  P.  3,  and 
loosen  the  set  screw  holding  the  bushings.  This  set  screw 
may  be  seen  in  the  side  of  the  casting  just  above  the  line 
leading  to  arrow  head  18795,  P.  3.  Having  loosened  the  set 
screw,  carefully  pry  off  the  bushing  toward  the  front,  shov- 
ing the  shaft  and  gear  along  with  it.  As  soon  as  you  have 
the  bushing  out  of  its  bearing  the  gear  and  shaft  can  be 
pulled  away. 

No.  37.— To  Remove  Revolving  Shatter  Bracket,  19491,  P. 
3,  first  follow  Instruction  No.  15.  Next  follow  Instruction 
No.  33.  Remove  four  'hexagon-headed  large  screws,  one 


FOR    MANAGERS   AND    OPERATORS  589 

of  which  is  seen  at  38,  P.  2.  This  releases  the  entire  mechan- 
ism from  its  supporting  casting.  Having  proceeded  thus  far, 
you  will  find  two  heavy  screws  at  the  lower  corners  of  the 
mechanism.  Remove  these  and  the  brackets  will  be  released 
from  the  mechanism. 

No.  38. — T^he  Entire  Mechanism,  that  is  to  say,  the  part 
which  frames  up  and  down,  may  be  removed  from  the  frame 
by  taking  out  the  mechanism  holding  screws  (four  of  them), 
one  of  "which  is  shown  at  38,  P.  2,  the  three  others  being 
in  corresponding  positions,  there  being  two  on  one  side  and 
two  on  the  other.  These  four  screws  hold  the  mechanism  to 
the  frame. 

No.  39.— Setting  the  Revolving  Shutter.  See  General  In- 
struction No.  18. 

No.  40. — Oiling.  See  General  Instruction  No.  1.  There  is 
one  oil  tube,  leading  to  the  intermittent  shutter  gear  bear- 
ings. The  top  of  this  tube  is  stopped  by  a  steel  ball  in  order 
to  keep  dirt  out.  Press  the  ball  down  with  the  nose  of  the 
oil  can,  and  the  oil  will  flow  into  the  tube.  A  bit  of  cotton 
should  be  kept  in  the  oil  hole  of  gear  19333,  P.  1,  to  keep 
out  dirt.  Beyond  this  no  special  instructions  are  necessary 
for  the  oiling  of  the  Edison  Model  D,  except  that  I  would 
advise  the  use  of  a  tolerably  heavy  lubricant  on  the  star  and 
cam. 

No.  41. — Lower  Shield,  18666,  P.  3,  may  be  removed,  to- 
gether with  its  hinge,  by  taking  out  two  screws  2798,  P.  3. 
Don't  take  out  the  hinge  pin.  If  you  do  you  are  very  likely 
to  have  a  hard  job  getting  the  spring  back  into  place. 

No.   42. — Adjusting  Sprocket  Idler   Rollers.     See    General 

Instruction  No.  12,  and   Instruction   No.  30. 

No.  43. — Cleaning  Sprockets.  See  General  Instruction 
No.  3. 

No.  44. — Worn  Sprocket  Teeth.  See  General  Instruction 
No.  8. 

No.  45. — Worn  Aperture  Plate.  See  General  Instruction 
No.  11. 

No.  46.— Two-Wing  vs  Three- Wing  Shutters.  See  General 
Instruction  No.  18. 

No.  47. — Adjusting  Tension  Springs.  See  General  Instruc- 
tion No.  9. 

No.  48. — End  Play  in  Intermittent  Sprocket.  See  General 
Instruction  No.  7. 


590 


MOTION    PICTURE    HANDBOOK 


No.  49. — Deposit  on  Tension  Springs.  See  General  In- 
struction No.  10. 

No.  50. — Lining  the  Sprockets.  See  General  Instruction 
No.  4. 


NAMES  AND  NUMBERS  OF  PARTS  FQR  THE 
EDISON  MODEL  D  MECHANISM 

Order   Parts  by  Numbers.     These  Numbers  Are   the  Manu- 
facturer's  Regular  Stock   Numbers. 


Parts  on  Plate  No.  1. 


18058 
18117 

18028 
19334 
19320 
19344 
19318 
19333 


19483 
18692 
18684 
18702 
18141 
16816 

2794 

18672 
2076 

17585 
2798 

18055 
18057 

16594 

18106 
18108 

16577 
18121 


Adj.      gear     shaft     bracket       18119 

(left). 
Upper       sprocket       tension 

roller     shaft. 
Frame  side   post    (short). 
Picture    gauge,    assembled. 
Film     guide     (left). 
Film    guide    screw. 
Film   spacer   (left). 
Revolving     shutter    driving 

shaft     and      mitre     gear, 

assembled. 

Cam   shaft  mitre   gear. 
Cam  shaft  bearings  (short). 
Cam  shaft. 

Intermittent   sprocket. 
Bushing  set  screw. 
Take-up        sprocket        with 

flanges. 
Take-up  roller  bracket  shaft 

set  screw. 

Film  protector  hinge  spring. 
Adj.    gear    bracket    friction 

screws. 
Adjusting       gear       bracket 

screw. 
Adjusting  gear  shaft  collar 

set   screw. 

Adj.  gear  shaft  collar. 
Adj.      gear     shaft     bracket 

(right). 
Upper  sprocket  shaft  pinion 

(helical). 

Upper   steel  sprocket  shaft. 
Upper         sprocket          shaft 

bracket. 
Large      intermediate      gear 

(helical). 

Upper  tension  roller  springs.    17587 


2782 
18026 

2076 

1133 

20242 

16575 

19439 
16574 

19317 
19319 
18687 
16582 
18141 
18138 
16569 

18113 
18111 
16585 

18709 
18066 
16589 
16811 
16584 

19306 

17950 
18117 
17949 


Upper  tension  roller  brack- 
et pin. 

Gear   guard   screws. 

Frame  side  long  post 
(drilled). 

Frame  side  post  screw. 

Frame   cap  screws. 

Picture  gauge  screw. 

Second  intermediate  pinion 
(helical). 

Cam  shaft  driving  gear. 

First  intermediate  pinion 
(helical). 

Film   spacer    (right). 

Film    guide    (right). 

Cam   shaft    pinion. 

Frame  side   cap. 

Bushing  set  screw. 

Cam  and  pin,  assembled. 

Large  driving  gear  (hel- 
ical). 

Star  sliaft. 

Star. 

External  revolving  shutter 
shaft  gear  (helical). 

Lower   Film    guard. 

Driving   crank  long   7^    in. 

Take-up  sprocket  shaft. 

Take-up   frame. 

Take-up  sprocket  shaft 
pinion  (helical). 

Take-up  tension  roller 
bracket. 

Steel  tension  roller  end. 

Tension   roller   shaft. 

Take-up  Steel  tension  roller 
body. 

Take-up  attachment  screw. 


Parts  on  Plate  No.  2. 


18047     Adjusting   lever.  19324 

19321     Film  gate  guard   (upper).  18193 

20636     Film  gate  guard  stop  screw         19331 

(upper). 
19353     Film  gate. 


Film   tension  bar. 

Film    gate    hinge   rod. 

Drop  shutter  clutch  shaft 
and  mitre  gear,  assem- 
bled. 


FOR -MANAGERS   AND    OPERATORS 


591 


18766     Film     gear     tension     roller 

bracket. 
17950     Film      gate      steel      tension 

roller  end. 
18117     Film     gate     tension     roller 

shaft. 
H949     Film      gate      steel      tension 

roller    body. 

17587     Take-up  attachment  screws. 
19312     Take-up        tension        roller 

bracket    spring. 
18666     Film    protector. 
18302     Upper  film  magazine  thumb 

screws. 

19159     Mechanism   support. 
17950     Upper    steel     tension    roller 

end. 
17949     Upper    steel     tension    roller 

body. 
16580     Large      intermediate      gear 

etud    (helical). 
2076     Frame   side   post   screw. 


19325     Upper   film    guard. 

16576     Second   intermediate   pinion 

stud    (helical). 

38     Mechanism   holding  screws. 
19494     Balance     wheel     and     cam 

shaft  pinion. 
16523     Gear  guard. 
18079     Large     driving     gear     stud 

washer. 
17804     Large     driving     gear     stud 

washer    screw. 
19410     External    revolving    shutter 

two-wing. 
18941     Take-up  steel  tension  roller 

bracket  sihaft. 
18090     Second   intermediate  pinion 

cotter    pin. 

16545     Mechanism    base. 
18049     Adjusting  gear. 
18052     Adj.    gear   shaft. 
19339     Upper  film  guard  roller. 
19325     Upper  film  guard. 


Parts  on  Plate  No.  3. 


18039     Slide    adj.    rack. 

18042     Slide      adj.      rack      bracket 

screw. 
207!6     Frame  side  post  screw. 

19489     Frame   side    (left). 

18031     Body  side   (left). 

18964  Automatic  drop  shutter, 
weight  and  counter 
balance. 

16588     External    revolving    shutter 

driving    gear. 

8141     Automatic       drop       shutter 
clutch    cover   screw. 

18795  Automatic  drop  shutter 
clutch  disc  driving  screw. 

19331  Drop  slhutter  clutch  shaft 
and  mitre  gear,  assem- 
bled. 

18778  Automatic  drop  shutter 
clutch  shaft  collar. 

187J1  Automatic  drop  shutter 
clutch  cover. 

16693  External  revolving  shutter 
shaft  with  gear,  assem- 
bled (helical). 

82     External    revolving    shutter 
set    Bcrews. 

16587  External  revolving  shutter 
intermediate  gear  (hel- 
ical). 

2053     Driving    chain    tension    link 
screw. 

19723     Driving   chain   tension  link. 
2798     Film  protector  hinge  screw. 

17992     Upper    steel    sprocket    with 
flanges. 


18118     Upper    steel     tension    roller 

bracket. 
18207     Film    gate    stop    screw    nut 

(upper). 

2782     Film    gate    stop    screws. 
18758     Film  gate  latch  and  spring 

stud,    assembled. 
20406     Film      gate      latch      screw, 

slhouldered. 

19256     Film    tension  bar   screws. 
18780     Automatic       drop       shutter 

bracket. 
18156     Film      gate     guard      screw, 

lower. 
18207     Film    gate   stop   screw    nut. 

2782     Film    gate    stop    screws. 
18779     Automatic       drop       shutter 

clutch     shaft     collar     set 

screw. 

18763     Film  gate  guard  (lower). 
18705     Star    shaft    bearing,    eccen- 
tric. 

18193     Film    protector  hinge   rod. 
16,814     Driving          chain          upper 

sprocket   for   9/32"   shaft. 
2817     Driving   chain    tension    link 

screw   washer. 

18667     Film    protector  hinge. 
18666     Film    protector. 
19346     Upper  film  guard  pins. 
19491     Ext.       rev.      shutter      shaft 

and    bracket     and    bush- 
ing,   assembled. 
18795     Automatic       drop       shutter 

clutch  disc  driving  screw. 
19498     Film     tension     bar     spring 

screw. 


592 


MOTION    PICTURE   HANDBOOK 


Machine  Take-Up 

The  take-up  of  a  projector  is  an  extremely  important  part  of 
the  mechanism,  although  until  quite  recently  it  seems  to  have 
.received  but  little  consideration  from  any  one,  except  the  pro- 
jection department  of  the  Moving  Picture  World,  which  has  for 
several  years  been  persistently  advocating  the  invention  and 
adoption  of  a  take-up  tension  equalizer. 

The  old  style  take-up  had  grievous  faults.  Selecting  the 
old  style  Edison  take-up  for  the  purpose  of  illustration,  parts 
of  which  are  shown  in  Fig.  283,  it  consists  essentially  of 
spindle  1  carried  by  bearing  4,  the  latter  clamped  in  a  cast- 


/     13 


Figure  283. 


ing  attached  to  the  mechanism,  or  in  some  machines  by  the 
lower  magazine.  Friction  disc  6  was  rigidly  attached  to 
spindle  1,  and  revolved  therewith.  Belt  wheel  8  was  mounted 
on  shaft  1,  upon  which  it  revolved  freely,  using  the  shaft 
merely  as  an  axle.  Seven  was  a  friction  washer,  usually 
made  of  fiber.  The  action  was  as  follows:  The  reel  was 
mounted  on  shaft  1,  to  which  it  was  locked  by  dowel  13,  the 
dowel  engaging  with  the  notch  in  the  reel  hub;  the  reel  was 
prevented  from  slipping  off  the  shaft  by  part  2.  Spring  12 
was  placed  on  the  shaft  and  compressed  by  collar  14,  which 
was  held  in  place  by  a  thumb  screw  therein  and  by  cotter 
pin  9.  Now  it  requires  but  a  moment's  study  of  this  assem- 
blage to  see  that,  since  disc  6  is  attached  rigidly  to  shaft  1, 
whereas  belt  wheel  8  revolves  freely  thereon,  when  belt 
wheel  8  is  driven,  power  will  be  imparted  to  shaft  1  through 
disc  6  exactly  in  proportion  to  the  pressure  with  which  the 
belt  wheel  is  clamped  against  disc  6,  or  rather  fibre  washer  7, 
which,  in  turn,  impinges  on  disc  6.  AH  this  is  quite  simple. 


FOR    MANAGERS   AND    OPERATORS 


593 


The  whole  trouble  with  the  take-up  proposition  lies  in  the 
fact  that,  whereas  the  film  is  fed  down  through  the  projector 
and  into  the  lower  magazine  at  a  uniform  speed  of  approxi- 
mately 60  feet  per  minute,  and  belt  wheel  8  is  necessarily 
driven  at  uniform  speed,  the  film  is  wound  on  a  reel  the 
diameter  of  which  is  very  small  at  the  beginning,  but  con- 
stantly increases  in  size.  Therefore  it  follows  that  in  order 
to  take  up  the  60  feet  per  minute  fed  to  it  the  reel  in  the 
lower  magazine  must  run  very  fast  when  the  film  roll  is 
small,  whereas  after  the  film  roll  on  the  lower  reel  has  be- 
come, say,  8  inches  in  diameter  the  reel  must  run  very  slowly, 
since  the  film  roll  is  then  more  than  2  feet  in  circumference. 

All  the  old  style  take-up  did  was  to  allow  sufficient  slippage 
between  belt  wheel  8  and  disc  6  to  a  accomodate  the  before 
described  condition.  When  the  take-up  first  started  to  re- 
wind there  would  be  little  or  no  slippage  between  these 
parts,  but  as  the  diameter  of  the  film  roll  increased,  slippage 
took  place,  which  allowed  the  reel  of  the  magazine  to  slow 
up,  although  belt  wheel  8  continued  to  revolve  at  its  regular 


Figure  284. 

speed.  The  objection  to  this  is  illustrated  in  Fig.  284.  At  X, 
Fig.  284,  we  see  the  film  coming  down  from  lower  sprocket  A 
and  beginning  to  wind  on  the  hub  of  empty  reel  D.  The  one- 
pound  weight  represents  the  pull  of  the  take-up,  which  is 
constant  throughout  the  run.  At  Y,  Fig.  284,  we  see  exactly 
the  same  thing,  except  that  the  film  roll  has  increased  to 


594  MOTION    PICTURE   HANDBOOK 

about  8  inches  in  diameter.  The  pull  on  levers  G  (repre- 
senting the  pull  of  the  take-up  belt)  being  the  same  all  the 
time,  it  requires  no  great  discernment  to  understand  that 
the  pull  on  the  film  at  X  will  be  a  good  many  times  that  ex- 
erted at  Y,  and  this  was  the  trouble  with  the  old  style  take-up. 
Tension  between  6,  7  and  8,  Fig.  283,  had  to  be  sufficient  to 
revolve  the  reel  under  conditions  shown  at  Y,  Fig.  284,  or  in 
other  words,  spring  12,  Fig.  283,  had  to  be  compressed  suffi- 
ciently to  provide  power  to  take  up  the  entire  reel  of  film, 
which  meant  that  at  the  beginning,  when  the  roll  was  small, 
the  strain  on  the  film  was  many  times  what  it  should  be. 
This  condition  had  a  tendency  to  (a)  cause  losing  of  the 
lower  loop;  (b)  exert  unnecessary  and  injurious  strain  on 
the  sprocket  holes  of  the  film,  thus  injuring  the  perforations; 
(c)  it  had  a  tendency  to  pull  weak  patches  in  two;  (d)  it  had 
a  very  decided  tendency  to  scratch  the  first  fifty  or  hundred 
feet  of  film. 

Of  late,  however,  new  and  improved  types  of  take-up  have 
been  invented,  and  are  in  operation  on  some  of  the  later 
models  of  projectors.  By  their  use  these  evils  are  either  re- 
duced or  eliminated.  See  the  various  mechanism  instructions. 

THREADING  THE  MACHINE 

All  machines  thread  alike  so  far  as  the  principle  involved 
is  concerned.  In  Fig.  285  the  idea  is  clearly  set  forth.  The 
film  comes  down  from  above,  passes  over  the  constantly 
running  top  sprocket,  forms  a  loop,  passes  down  from  the 
aperture  to  intermittent  sprocket,  forms  another  loop,  and 
passes  over  the  lower,  constantly  running  sprocket,  and 
thence  down  into  the  lower  magazine.  The  two  loops  must 
be  long  enough  so  that  when  the  film  moves  down  three- 
quarters  of  an  inch  it  will  not  be  stretched  tight  between 
the  upper  sprocket  and  aperture  plate,  but  there  will  still 
be  a  loop  left,  and,  conversely,  the  lower  loop  must  be  long 
enough  so  that  during  the  time  the  film  stands  still  over  the 
aperture  plate  the  lower  sprocket  will  not  pull  the  film 
tight  between  itself  and  the  intermittent  sprocket.  This 
much  is  essential,  but  in  practice  the  loops  are  carried  con- 
siderably longer,  or  larger,  the  proportions  shown  in  Fig. 
285  being  approximately  correct.'  Fig.  285  shows  the  thread- 
ing of  the  Power's  Six  machine. 

The  operator  should  thread  his  machine  so  that  one  picture 
or  one  title-space  will  be  in  frame  over  the  aperture  of  the 
machine,  in  order  that  when  the  machine  is  started  the  picture 
or  title  will  be  "in  frame"  on  the  screen.  To  do  this  a  small 


FOR    MANAGERS   AND    OPERATORS 


595 


electric  light  connected  to  the  house  supply  may  be  arranged, 
so  that  it  may  be  swung  in  front  of  the  objective  lens  when 
threading,  and  moved  out  of  the  way  when  the  job  is  finished. 

-sL 


Figure  285. 

It  should  be  so  arranged  that  swinging  the  lamp  in  front  of 
the  lens  will  automatically  light  it  and  moving  it  away  will 
break  the  circuit  and  put  it  out.  A  two  C.  P.  lamp  is  plenty 
bright  enough. 


596  MOTION    PICTURE   HANDBOOK 

Another  method  followed  by  some  operators,  and  the  one 
which  really  is  best,  is  to  fix  a  miniature  battery  lamp  inside 
the  mechanism,  so  that  it  is  just  below  the  back  end  of  the 
objective  lens.  This  lamp  is  connected  to  one  or  two  dry 
cells,  and  as  it  burns  only  for  a  few  seconds  while  threading, 
the  cells  will  last  for  a  long  time.  This  plan,  however,  can- 
not be  followed  with  all  mechanisms,  since  with  the  Simplex, 
for  instance,  the  light  ray  between  the  aperture  and  lens  is 
entirely  inclosed. 

Still  another  plan  is  to  notice  where  the  dividing  line 
comes  with  relation  to  the  top  of  the  aperture  when  the 
picture  is  in  frame  over  the  aperture,  but  this  has  the  dis- 
advantage that  you  cannot  always  see  the  dividing  line.  On 
the  whole  the  light  scheme  is  much  the  better. 

NO  MATTER  WHAT  PLAN  IS  ADOPTED,  HOWEVER,  THE  PAINSTAKING, 
CAREFUL  OPERATOR  WILL  NEVER  START  HIS  PICTURE  OUT  OF  FRAME. 
TO  DO  SO  BRANDS  HIM  AS  CARELESS  AND,  NO  MATTER  HOW  YOU  LOOK 
AT  IT,  CARELESSNESS  SPELLS  INCOMPETENCY. 

FILM  CONTAINERS 

In  many  cities  the  law  requires  that  film  not  in  use  on 
the  machine  shall  be  kept  in  fire  proof  steel  containers. 

B.  Steinhauser,  Terre  Haute,  Ind.,  is  the  inventor  of  the 
container  shown  in  Fig.  286.  This  magazine  is  substantially 
made,  and  has  the  advantage  of  being  in  sections,  each  sec- 
tion independent  of  the  other.  The  one  shown  in  Fig.  286 
is  composed  of  three  sections  each  entirely  independent  of 
the  other.  They  are  attached  to  the  wall  by  means  of  lugs 
shown,  and  attached  to  each  other  by  means  of  flat  hooks 
on  one  side  of  each  container  which  engages  with  a  suitable 
receptacle  on  the  other  side.  Under  the  film  compartment 
is  an  opening  designed  to  contain  blotting  paper  moistened 
with  water.  The  container  sets  at  a  slope  so  that  the  reel 
when  placed  in  will  immediately  roll  out  again  unless  the 
door  is  closed,  the  latter  being  controlled  by  a  plunger  shown 
at  the  bottom  of  the  magazine.  Raise  the  plunger,  and  the 
door  automatically  opens  and  the  reel  rolls  out.  The  ad- 
vantage  of  this  form  consists  in  the  fact  that  if  a  six  reel 
program  is  used  on  two  machines,  three  reels  on  each  ma- 
chine, three  of  the  containers  can  be  placed  near  one  machine 
and  three  near  the  other,  thus  saving  the  operator  steps. 
Also  in  case  of  fire  the  operator  can  grab  the  container  by 
the  handle  shown  at  the  top,  lift  it  off  the  nail,  and  carry  it 
outside  instantly. 


FOR  MANAGERS  AND  OPERATORS 


597 


The  "Safety  First"  Film  Magazine,  manufactured  in  Balti- 
more, Md.,  is  an  excellent  operating  room  film  container.  It 
is  cylindrical  in  form,  its  frame  being  made  of  cast  iron,  and 
its  lower  ends  and  compartment  walls  of  sheet  steel  with 
one-half  inch  air  spaces  between  each  compartment  at  each 
end,  and  on  the  lower  half. 


Figure  286. 


The  magazine  is  made  to  hold  any  number  of  reels  de- 
sired. It  occupies  but  little  space,  is  claimed  to  be  thoroughly 
fireproof  and  has  many  points  to  commend  it.  The  cylin- 
drical form  prevents  its  being  used  as  a  catch-all  for  odds  and 
ends. 

In  operation  when  the  compartment  doors  are  lifted  a  wire 
loop  automatically  raises  a  curved  casting  in  the  bottom  of 
the  compartment,  thus  automatically  raising  the  reel  half 
way  out  of  the  magazine. 


598 


MOTION    PICTURE    HANDBOOK 


The  Spotlight 

IT  is  no  unusual  thing  for  the  operator  to  be  called  upon 
to  operate  a  spotlight,  similar  to  the  one  illustrated  in 
Fig.  287.  This  device  consists  of  a  metal  base  and  up- 
right standards  upon  which  are  mounted  the  rheostat  and 
switch.  The  upper  end  of  this  standard  supports  a  lamp- 
house  in  such  way  as  it  may  be  swung 
or  tilted  to  throw  the  light  beam  in  any 
desired  direction.  Inside  the  lamphouse 
is  an  ordinary  arc  lamp,  very  similar  to 
those  used  in  moving  picture  projection 
machine  lamphouses,  but  lacking  the 
forward  and  backward  screw  adjustment. 
Spotlight  rheostats  usually  are  designed 
to  deliver  12  to  15  amperes  of  current. 
In  ordering  ,a  spotlight  it  is  necessary 
that  the  voltage  of  your  current  and  the 
approximate  distance  from  the  operating 
room  to  the  stage  be  given,  the  latter 
in  order  -that  a  proper  lens  may  be 
selected.  If  direct  current  is  used  the 
upper  carbon  arm  of  the  lamp  must  be 
connected  to  the  positive  wire. 

The  spotlight  has  a  single  plano-con- 
vex lens  6  inches  in  diameter,  and  the 
size  of  the  spot  at  the  stage  is  changed 
simply  by  pulling  the  lamp  back  or 
shoving  it  ahead.  The  spotlight  may 
be  used  for  a  spot  or  for  a  flood  cover- 
ing the  entire  stage. 

The  spot  should  be  round  and  free  from  ghost,  but  it  will 
be  found  impossible  to  eliminate  all  the  color  from  its  outer 
edges.  The  shape  of  the  spot  as  well  as  its  freedom  from 
ghost  will  depend  very  largely  on  how  the  carbons  are  set. 
They  should  be  set  practically  the  same  as  you  would  set 
them  for  a  projection  arc,  varying  the  advancement  of  the 
upper  carbon  tip  with  relation  to  the  lower,  as  well  as  the 
angle  of  the  lamp  itself,  until  the  'best  possible  results  are 
obtained.  It  is  better  to  use  a  half-inch  cored  carbon  above 
and  .a  three-eighth-inch  below,  if  you  can  get  them.  Five- 
eighth  carbons  can  be  made  to  do,  but  are  too  large  for  the 
amperage  ordinarily  used  on  a  spotlight.  For  alternating 
current,  however,  I  believe  two  half-inch  cored  carbons  will 
give  the  best  results,  though  the  amperage  will  have  to  be 


Figure  287. 


FOR    MANAGERS    AND    OPERATORS 


599 


boosted  to  fully  30  in  order  to  approximate  the  D.  C.  spot. 
Following   an   actor  with    a   spotlight   is   purely  a  matter    of 


Figure  288. 

practice.     There  is  nothing  particularly  difficult  about  it,  the 
hard  part  being  to  get  and  maintain  a  clear  round  spot. 

The  hole  in  the  operating  room  wall  should  be  about  16 
inches  square,  or  16  inches  in  diameter  if  round.  A  color- 
wheel  may  be  obtained  from  any  dealer  in  theatrical  supplies, 
and  is  a  very  necessary  adjunct  to  the  spotlight.  By  combin- 
ing the  use  of  the  spotlight  with  a  dissolving  stereopticon, 
using  slides  in  the  latter  made  from  etched  pattern  glass  and 


\ 


o 


Figure  289. 

rough  glass  such  as  is  used  in  doors  and  windows,  and  care- 
fully made  metal  slides  producing  a  star  effect  or  something 
of  that  sort,  some  very  beautiful  effects  can  be  had  by  pro- 
jecting with  both  stereopticon  lamps  and  the  spotlight  at 
the  same  time. 

Spotlight   connection    is    usually   made    by    using    what    is 


6pO  MOTION   PICTURE   HANDBOOK 

known  as  "stage  cable,"  a  heavily  insulated  twin  wire.  These 
wires  should  be  not  less  than  No.  8. 

Fig.  288  illustrates  the  optical  system  of  a  spotlight.  The 
main  difference  in  handling  a  spot  with  A.  C.  is  that  it  is 
almost  impossible  to  avoid  a  blue  ghost  at  the  top  of  the 
spot,  or  a  double  spot,  the  latter  being  due  to  the  double 
crater. 

It  is  possible  to  make  a  fairly  satisfactory  home-made 
spotlight  by  using  an  old  projection  machine  lamphouse. 
You  can  fit  up  the  standard  the  same  as  the  one  shown  in 
Fig.  289,  using  any  convenient  floor  base,  and  arranging  to 
attach  the  lamphouse  to  the  standard  in  such  way  that  you 
can  tilt  it  and  swing  it  from  side  to  side.  The  standard  is 
made  by  having  a  hollow  stem  below,  with  a  small  one  in- 
side it  which  can  be  raised  or  lowered  and  clamped  in  place 
by  means  oi  a  collar  and  set  screw.  Two  pieces  of  different 
size  gaspipe  make  an  excellent  standard.  One  must  fit  in- 
side the  other. 

The  Stereopticon 

THE  Stereopticon  consists  of  a  lamphouse  and  lamp,  a 
condenser,  a  slide  carrier  and  an  objective  lens. 
The  slides  used  in  America  measure  3%  inches  by  4 
inches  overall,  with  a  mat  opening  2%  by  3  inches.  In  foreign 
countries  the  slides  are  for  the  most  part  square,  though  I 
do  not  remember  the  exact  dimensions. 

With  moving  pictures  electric  light  forms  the  only  satis- 
factory illuminant.  With  the  Stereopticon  excellent  results 
may  be  had  by  the  use  of  ozo-carbi  light,  lime-light,  or  even 
with  acetylene  gas;  this  by  reason  of  the  fact  that  whereas 
in  projecting  moving  pictures,  using  a  modern  mechanism, 
fully  50  per  cent  of  the  light  is  cut  by  the  revolving  shutter, 
and,  moreover,  there  is  a  large  loss  of  light  at  the  spot, 
which  must  of  necessity  overlap  the  aperture  by  consider- 
able, with  the  Stereopticon  practically  all  the  light  pass- 
ing through  the  mat  opening  of  the  slide  finds  its  way  to  the 
screen,  and  the  only  light  loss  by  overlapping  is  a  slight  loss 
at  the  outer  edge  of  the  condensers  where  the  light  is  weak- 
est. 

In  moving  picture  projection  the  picture  (film)  is  from  one 
to  two  feet  away  from  the  condensing  lens,  whereas  with  the 
Stereopticon  the  picture  is  right  up  as  close  as  it  can  be  got 
to  the  frbnt  surface  of  the  condenser.  With  moving  picture 
projection  the  objective  is  comparatively  near  the  film,  where- 


FOR    MANAGERS   AND    OPERATORS 


601 


as  with  the  stereopticon  it  is  a  considerable  distance  (from  8 
to  30  inches)  away;  incidentally,  this  is  the  reason  why 
a  cracked  condenser  lens  will  show  in  the  stereopticon 
projection,  whereas  it  will  not  show  in  the  moving  picture. 
In  both  cases  it  is  the  picture  which  is  focused  at  the  screen, 
and  the  condenser  being  so  close  to  the  picture  in  stereopticon 
projection,  is  focused  at  the  screen  therewith.  Hence  any 
imperfection  like  a  crack  will  show. 

In  the  old  days,  and  still  to  some  extent,  the  projection 
machine  carried  a  stereopticon  attachment,  usually  single, 
though  sometimes  dissolving.  The  single  stereopticon  at- 
tachment consists  merely  of  an  objective  lens  attached  to 
the  side  of  the  moving  picture  mechanism,  and  an  arrange- 
ment whereby  the  lamphouse  may  be  shoved  over  to  center 
the  light  ray  from  the  condenser  in  the  center  of  the  stereop- 
ticon lens.  This,  however,  brings  about  a  complication,  since 
if  the  same  amperage  used  for  moving'  picture  projection  be 
used  for  stereopticon  projection,  there  is  great  likelihood  of 
breaking  the  slides  by  reason  of  excessive  heat.  It  there- 
fore follows  that,  while  slides  which  will  only  remain  in  the 
light  five  or  six  seconds  may  be  projected  with  the  heavy 
amperage  used  for1  moving  picture  projection  without  serious 
danger  of  breakage,  if  song  slides,  especially  chorus  slides, 
are  to  be  projected,  it  will  be  necessary  to  reduce  the  current, 
else  the  slides  will  most  likely  crack.  This  may  be  accom- 
plished in  a  number  of  ways,  depending  on  whether  the 
current  is  taken  through  a  rheostat,  a  transformer,  a  motor 
generator  set  or  a  dissolver.  If  current  is  taken  from  power 


Figure  290. 

lines  through  rheostats,  then  it  is  only  necessary  to  connect 
in  an  additional  resistance  as  per  Fig.  290,  in  which  A  is 
a  single-pole,  single-throw  switch.  By  opening  this  switch 


602 


MOTION    PICTURE    HANDBOOK 


the  current  is  forced  through  the  additional  resistance,  which 
should  be  qf  such  amount  that  the  current  flow  will  be  re- 
duced to  between  12  and  15  amperes,  that  being  ample  for  stereop- 
ticon  projection.  If  a  transformer  is  used,  then  the  current 


Figure  291. 

may  be  sufficiently  reduced  by  throwing  in  on  the  low  notch, 
which  with  most  transformers  will  give  from  35  to  40  am- 
peres A.  C;  a  little  high,  but  it  will  do.  If  a  motor  genera- 
tor set  is  used  the  thing  can  usually  be  done  with  the  field 


FOR    MANAGERS   AND    OPERATORS 


603 


rheostat,  or  if  that  method  is  unsatisfactory,  then  a  rheostat 
can  be  arranged  so  that  the  operator  can  cut  it  in  circuit  by 
means  of  a  switch.  With  the  later  type  mercury  arc  rectifier 
there  is  an  arrangement  for  varying  the  amperage  instantly, 
though  it  cannot  be  brought  down  low  enough  for  stereop- 
ticon  projection.  The  current  may,  however,  be  reduced  by 
arranging  resistance  so  it  may  be  cut  into  circuit  with  the 
D.  C.  circuit  of  the  rectifier. 

In  stereopticon  projection  one  fundamental  proposition  is  to 
keep  your  slides  clean.  When  using  a  single  stereopticon  don't 
drop  a  slide  into  the  carrier  like  you  would  throw  a  brick  on 
a  sidewalk,  because  if  you  do  the  picture  being  projected 
will  jump  around  like  a  ship  on  a  stormy  ocean.  With  a 
properly  matched  lens  system  there  is  no  earthly  excuse  for 
any  shadow  or  discoloration  of  the  light  on  the  screen.  The 
field  should  be  absolutely  clear,  and  the  picture  should  be  as 
steady  as  a  rock  during  the  entire  projection. 

It  is  not,  however,  my  intention  to  go  extensively  into 
stereopticon  projection  with  the  single  lamp,  because  there 
is  little  of  that  done  nowadays.  The  modern  method  of 
projecting  stereopticon  slides  is  by  means  of  a  dissolver. 

The  Dissolver. — The  dissolving  stereopticon,  Fig.  291,  con- 
sists of  two  separate  stereopticons  mounted  on  one  base, 
usually  one  above  the  other,  with  shutters  in  front  of  the 
lenses  so  joined  that  the  opening  of  one  shutter  closes  the 
other,  and  vice  versa,  thus  gradually  closing  one  lens  and  at 
the  same  time  and  in  the  same  degree  opening  the  other. 

Each  lamp  should  be  connected  to  a  source  of  separate 
electric  supply,  exactly  the  same  as  though  the  other  lamp 
did  not  exist. 


Figure  292. 

Fig.  292  illustrates  the  method  of  connecting  dissolver 
lamps;  1  is  the  main  operating  room  switchboard  and  fuse 
cabinet;  2  are  cut  out  blocks  and  fuses;  3-3  are  the  operating 
switches,  one  on  each  circuit;  4-4  are  the  rheostats,  one  on 
each  circuit;  5-5  are  the  dissolver  lamps. 

When  a  machine-dissolver  is  used  which  utilizes  the  pro- 
jection machine  arc  for  the  illuminant  of  the  lower  stereop- 


604  MOTION    PICTURE   HANDBOOK 

ticon,  a  condition  usually  arises  which  requires  special  treat- 
ment. As  a  general  proposition  much  higher  amperage  is 
required  for  the  moving  picture  projection  arc  than  is  either 
necessary  or  desirable  for  use  with  a  dissolver.  Either  the 
upper  dissolver  lamp  must  be  supplied  with  amperage  equal 
to  the  projection  machine  arc  or  else  the  projection  machine 
arc  amperage  must  be  reduced,  since  high  amperage  on  one 
dissolver  lamp  and  low  on  the  other  would  utterly  ruin  the 
effect  on  the  screen.  As  has  been  said,  under  ordinary  con- 
ditions, 15  amperes  D.  C.  is  ample  for  stereopticon  projec- 
tion. If  amperage  much  in  excess  of  this  is  used  there  is 
danger  of  excessive  slide  breakage,  and  this  would  be  a  very 
serious  matter  if  the  slides  are  fine  hand-colored  art  slides 
such  as  those  sometimes  used  by  traveling  lecturers. 

Referring  to  Fig.  290,  let  us  assume  the  upper  rheostat 
to  be  of  15  ampere  capacity  and  the  lower  35.  Under  this 
condition  the  dissolving  effect  would  be  something  of  a  joke, 
but  by  inserting  sufficient  additional  resistance  in  series 
with  the  lower  rheostat  to  cut  the  amperage  down  to  an 
equal  value  to  that  delivered  by  the  upper  resistance  (15), 
we  thus  secure  an  equal  amperage  at  each  lamp  and  the  same 
screen  brilliancy  from  both  stereopticons. 

It  is  possible  to  accomplish  the  desired  result  by  means 
of  an  adjustable  rheostat  which  will  deliver  35  amperes  maxi- 
mum and  18  amperes  minimum.  This,  however,  is  not  the 
best  way,  principally  because  the  rheostat  would  probably 
have  to  be  built  specially  for  the  purpose,  and  that  would  be 
quite  costly,  since  special  apparatus  usually  is  expensive. 
The  more  practical  and  effective  way  is  to  insert  an  additional 
rheostat,  as  indicated  in  Fig.  290,  of  suc'h  resistance  that 
the  two  rheostats  combined  will  equal  the  resistance  of  the 
upper  rheostat,  placing  a  single-pole,  single-throw  switch  at 
A.  It  needs  but  a  glance  to  show  that  when  switch  A  is  open 
the  current  must  pass  through  both  resistances,  whereas  clo"- 
ing  switch  A  cuts  the  extra  resistance  out. 

Where  a  combined  machine  and  dissolver  is  used  on  A.  C, 
taking  current  through  an  economizer,  it  is  possible  to  oper- 
ate both  lamps  of  the  dissolver  from  one  economizer,  though 
it  is  rather  difficult  to  handle  the  light;  also  it  is  somewhat 
uncertain  and  requires  practice.  Unless  handled  skillfully 
the  arcs  will  go  out.  This  may  be  done  in  several  ways,  one 
of  which  is  illustrated  in  Fig.  293,  in  which  A  is  the  econ- 
omizer and  B  a  double-throw,  single-pole  knife  switch.  When 
this  switch  is  thrown  over  to  the  right  the  upper  lamp  is 
cut  out,  though  its  lower  carbon  arm  is  still  "alive."  When  the 


FOR    MANAGERS    AND    OPERATORS 


605 


switch  is   thrown   the   opposite  way  the  current   must  pass 
through    both   lamps.      It   is    then   necessary    to    freeze    the 


Figure  293. 

carbons  of  one  lamp  while  the  arc  is  struck  on  the  other, 
after  which  the  carbons  of  the  second  lamp  may  be  separated 
and  the  second  arc  struck. 

This  can  be  and  is  done,  but,  as  I  h^ve  said,  it  is  difficult  to 
handle  the  arcs,  and  unless  one  has  had  considerable  practice 
there  are  likely  to  be  times  when  the  picture  on  the  screen 
will  suddenly  vanish.  The  same  thing  might  be  done  with 
rheostats,  though  there  is  ordinarily  no  reason  for  burn- 
ing the  arcs  in  series  where  current  is  taken  through 
resistance.  By  the  connection  shown  in  Fig.  293  the  resist- 
ance of  the  additional  arc  operates  very  materially  to  de- 
crease the  amperage. 

Dissolver  Shutter. — The  dissolving  shutter  of  a  stereop- 
ticon  is  a  very  simple  contrivance,  and  an  efficient  shutter 
may  be  made  by  any  operator,  though  excellent  dissolver 
shutters  may  now  be  had  and  are  not  very  expensive  either. 
The  effect  produced  by  them  is,  however,  I  think,  not  ap- 
preciably better  than 
that  produced  by  the 
well  designed  home- 
made article. 

In  Fig.  294  we  see 
two  types  of  dissolving 
shutter,  A  being  made 
of  metal,  and  B  either 
of  metal  or  wood.  The 
construction  is  so  plain- 
ly shown  that  a  de- 
scription  is  hardly  nec- 
essary.  A  consists  of 
two  pieces  of  sheet 
metal  riveted  to  a  bar 
(in  which  is  hole  X  for 


%/ 

B 

Figure  294. 


606  MOTION    PICTURE   HANDBOOK 

bolt  upon  which  it  swings)  to  which  is  also  attached  handle 
Y.  The  edges  of  the  shutter  are  cut  into  saw-teeth  two 
inches  deep,  and  the  shutter  must  swing  far  enough  so  that 
the  light  from  one  lens  is  entirely  shut  off  when  the  other 
is  open,  and  the  shutter  must  be  so  located  that  when  it  is 
in  the  position  shown  approximately  one-half  of  the  light 
from  each  lens  will  be  coming  through.  It  is  attached  to 
the  wall  by  bolt  X  so  that  it  will  swing  in  front  of  the  lens. 
Shutter  B  may  be  made  of  lumber,  asbestos  board  or  metal. 
It  is  quite  efficient.  Its  length  must  be  such  that  when  in 
the  position  shown  one-half  the.  light  from  eac'h  lens  will  pass 
through. 

Many  operators  who  have  two  machines  with  a  stereop- 
ticon  attachment  on  each  work  the  dissolving  effect  by  fixing 
a  shutter  somewhat  after  the  fashion  of  half  of  shutter  A, 
Fig.  294,  in  front  of  each  lens  and  connecting  the  two  by 
means  of  a  bar  or  cord.  It  is  the  same  thing  exactly,  only 
the  lenses  are  about  three  feet  to  four  feet  apart,  therefore 
the  mechanical  means  of  rigging  the  shutters  'have  to  be  a 
little  different.  It  may  be  accomplished  by  hanging  the  two 
shutters  in  grooves  and  connecting  them  by  a  cord  running 
through  pulleys  on  the  ceiling,  or  in  any  other  way  that  the 
ingenuity  of  the  operator  may  suggest. 

Dissolving  Moving  Picture. — In  this  connection  many  oper- 
ators who  run  two  machines  disso1ve  one  reel  into  the  next 
by  fixing  a  shutter  arrangement  similar  to  that  suggested  for 
separate,  single  stereopticons,  also  some  operators  connect 
their  dowser  handles  by  means  of  cords  running  to  the  ceil- 
ing, so  that  opening  one  closes  the  other.  I  only  give  the 
idea,  since  local  conditions  will  call  for  different  mechanical 
treatment  and  the  operator  who  has  not  ingenuity  enough  to 
rig  up  things  of  this  kind  has  no  business  in  an  operating 
room  anyhow.  I  might  add  that  there  is  a  patent  dissolving 
arrangement  which  utilizes  this  idea. 

Color  Wheel. — The  stereopticon  or  dissolver  may  readily 
be  fitted  with  home-made  color  wheels  so  that  colored  lights 
may  be  thrown  on  the  stage  or  screen.  All  that  is  necessary 
is  to  take  off  one  side  of  an  old  reel,  leaving  the  hub  attached 
to  the  other  side.  Place  the  two  sides  together  so  that  the 
holes  match,  with  the  hub  on  the  outside.  With  the  two 
held  together  in  this  position  drill  four  quarter-inch  holes 
equidistant  from  eac'h  other,  and  a  half-inch  from  the  edge 
of  the  reels,  these  to  receive  small  stove  bolts.  Cover  three 
of  the  openings  in  the  reel  side  with  colored  gelatine,  say 
canary  yellow,  a  light  red,  and  any  other  suitable  tint,  leav- 


FOR    MANAGERS    AND    OPERATORS  607 

ing  one  hole  open  through  which  to  project  the  clear,  white 
light  or  the  slides.  Clamp  the  sides,  with  the  gelatine  be- 
tween, together  with  the  bolts,  and  attach  to  the  wall  by 
means  of  a  spindle,  so  that  when  the  whole  is  revolved  the 
openings  will  come  successively  in  front  of  the  lens.  The 
open  hole  will  allow  the  projection  of  the  white  light  and 
the  stereo  picture  as  usual. 

Matched  Lenses. — It  is  absolutely  necessary  that  the  lenses 
of  a  dissolver  be  carefully  matched,  so  that  both  lenses  will 
project  a  picture  of  exactly  the  same  size,  when  the  two 
are  working  at  a  given  distance  from  the  screen;  also  they 
must  be  so  set  that  the  pictures  projected  by  each  lens  will 
make  perfect  "register" — that  is  to  say,  occupy  exactly  the 
same  space  on  the  screen.  To  adjust  the  register  of  the 
lenses,  first  set  the  lower  lens  so  that  the  picture  occupies 
the  proper  position  on  the  screen,  and  then  adjust  the  upper 
lens  to  match.  Do  this  with  the  light  from  both  stere- 
opticon  lamps  projected  to  the  screen.  One  way  to  test 
the  register  of  lenses  is  to  make  two  metal  slides  that  will 
fit  snugly  in  the  slide  carrier.  Now  having  clamped  the 
two  slides  together  punch  four  small  nail  holes,  one  in  each 
corner,  about  where  the  corner  of  an  ordinary  standard  slide 
would  be.  These-  holes  must  be  drilled  while  the  slides  are 
clamped  together  or  held  together  so  that  their  edges  are 
even  all  round. 

Place  one  slide  in  the  upper  carrier  and  the  other  in  the 
lower.  Disconnect  the  dissolver  shutter,  open  both  lenses, 
and  project  the  light  from  both  lamps  to  the  screen;  adjust 
the  lenses  so  that  the  light  from  the  holes  in  the  two  slides 
register  with  each  other.  This  same  thing  can,  of  course, 
be  done  by  placing  an  ordinary  stereopticon  slide  in  the 
upper  carrier,  marking  the  edge  of  the  picture  on  the  screen 
and  then  placing  the  same  slide  in  the  lower  carrier  and 
making  the  lines  match.  But  the  same  slide  must  be  used, 
or  two  slides  the  mats  of  which  are  exactly  matched  and 
in  exactly  the  same  position  in  the  slide.  The  metal  slide 
scheme  is  the  better  one,  because  if  you  use  two  slides  there 
might  be  a  slight  variation  in  their  mats  which  would 
render  the  result  of  the  test  of  no  value.  It  might  even 
cause  you  to  reject  two  lenses  which  were  really  perfectly 
matched;  also  if  you  used  one  slide  and  it  did  not  fit  the 
carrier  snugly  it  might  not  occupy  exactly  the  same  position 
in  one  carrier  that  it  did  in  the  other  and  that  would  render 
the  test  of  no  value.  But  with  two  metal  slides  which  fit  the 


608  MOTION   PICTURE   HANDBOOK 

carrier,  snugly,  and  with  matched  holes  drilled  you  can  de- 
pend upon  the  result. 

Caution:  When  using  drilled  slides  as  above  make  a  file 
mark  on  the  top  edge  of  both  while  they  are  clamped  to- 
gether and  see  to  it  that  these  marks  are  both  up  and  toward 
the  lens  when  the  slides  are  in  the  carrier.  If  one  of  them 
is  turned  around  the  holes  won't  match. 

It  is  essential  that  the  slide  carriers  be  so  adjusted  that 
the  picture  is  level  on  the  screen.  This  may  be  accomplished 
by  raising  or  lowering  one  side  of  the  carrier,  blocking  it 
in  place  with  some  non-inflammable  substance,  first  being 
certain  the  dissolver,  as  a  whole,  sets  perfectly  level.  The 
slide  carrier  should  set  as  close  to  the  condenser  as  you  can 
get  it.  If  your  picture,  which  <has  been  all  right  before, 
suddenly  registers  too  far  over  one  way  or  the  other,  it  is 
likely  the  slide  carrier  has  slipped  endwise. 

Patent  Dissolving  Carriers. — For  use  with  single  lamps 
there  are  a  number  of  patent  slide  carriers  on  the  market 
which  either  effect  a  very  quick  change  of  the  slide  or  pro- 
duces to  some  slight  extent  a  dissolving  effect.  The  best 
of  these  carriers  I  have  seen  is  the  "Ingento,"  made  by  a 
Chicago  manufacturer.  It  is  to  be  recommended  for  use 
with  single  lamps.  It  is  well  made,  comes  ;n  wood  or  metal, 
and,  rightly  handled,  produces  an  effect  as  nearly  resembling 
dissolving  as  can  be  accomplished  with  a  single  lamp.  It  is 
for  use  with  the  single  machine  only,  having  no  special  value 
when  used  with  a  dissolver. 

The  Picture.— Given  proper  equipment  there  is  ordinarily 
no  excuse  for  anything  but  perfect  stereopticon  projection. 
Yellow  corners  in  a  stereo  picture  or  a  ghost  in  its  center 
are  merely  evidence  that  the  operator  is  too  lazy  properly  to 
adjust  his  light  or  lias  not  sufficient  knowledge  properly  to 
match  up  his  stereo  lens  system.  The  objective  of  the 
stereopticon,  if  more  than  10  inches  E.  F.,  should  always 
be  what  is  commonly  known  as  "half  size." 

Where  a  combined  stereopticon  and  picture  machine  is 
used  it  will  frequently  be  found  necessary  to  move  the  lamp 
forward  or  back  slightly  with  relation  to  the  condensers  when 
shoving  over  to  the  stereo  picture.  If  this  is  not  observed 
there  will  be  dark  corners  in  the  picture. 

The  reason  that  a  stereopticon  lens  to  give  a  picture  the 
same  width  as  the  moving  picture  at  the  same  distance  is  of 
much  longer  focal  length  than  the  moving  picture  objective 
is  that  in  one  case  the  aperture  (slide  mat)  is  3  inches  wide, 
whereas  in  the  other  it  is  less  than  1  inch  in  width. 


FOR    MANAGERS   AND    OPERATORS 


609 


Figure  295. 


Stereopticon  Slides. — A  stereopticon  slide  consists  of  two 
pieces  of  thin  glass,  4  inches  by  4^4  inches,  bound  together 
with  gummed  paper.     Between  these  is  placed  a  paper  mask, 
called     a     mat,     which 
serves    the    purpose    of 
outlining      the     photo- 
graph. 

On  one  of  these 
glasses  is  a  photo- 
graphic emulsion,  upon 
which  has  been  printed 
a  positive  photograph 
Zy^  by  4  inches  in  size, 
which  the  paper  mask 
has  reduced  to  stand- 
ard size,  3  by  2^4 
inches.  Mats,  however, 
vary  in  size,  that  given 
merely  being  the  stand- 
ard article  ordinarily 
used  for  advertising  and  song  slides.  The  photograph  may 
or  may  not  be  colored.  If  it  is  the  coloring  is  done  by 
applying  water  colors  by  hand  to  the  photograph.  The  sec- 
ond glass  is  just  a  clear  piece  of  thin  glass,  called  a  cover 
glass. 

Ordinarily  there  are  some  words,  an  ornamental  design  or 
decoration  printed  on  one  side  of  the  mat,  and  this  -side  of 
the  mat  is  usually,  though  not  always,  red,  white,  gray  or 
black.  This  is  what  is  called  the  "mat  side"  of  a  slide,  and 
it  is  the  side  which  goes  toward  the  light. 

Fig.  295  shows  the  mat  side  of  the  slide.  The  other  side 
of  the  slide  is  shown  in  Fig.  296.  The  slide  must  be  placed 
in  the  carrier  in  an  inverted  position,  with  the  mat  side 
toward  the  light.  If  the  other  side  is  placed  toward  the 
light,  then  all  reading  matter  thereon,  such  as  signs  on 
buildings,  will  read  backward. 

Handling  Slides. — The  first  and  cardinal  law  applying  to 
stereopticon  projection  is  keep  the  slides  clean.  The  operator 
must  remember  that  every  fingermark,  every  spot  of  dust, 
oil,  or  anything  else  on  the  surface  of  a  slide,  will  show  on 
the  screen,  particularly  if  it  happen  to  be  on  a  clear  space 
such  as,  for  instance,  a  sky.  How  often  I  have  sat  in  a 
theatre  and  watched  the  operator  project  what  was  or 
would  have  been  a  beautiful  stereopticon  picture,  but  on  the 
surface  of  the  slide  was  from  one  to  half  a  dozen  dirty,  black 


610  MOTION    PICTURE   HANDBOOK 

fingermarks.  There  is  but  one  term  which  properly  can  be 
applied  to  this  kind  of  work,  and  that  is  disgusting. 

By  all  means  keep  your  stereopticon  slides  clean.  Unless  you 
do  the  result  on  the  screen  will  instantly  brand  you  as  a  sloppy 
workman. 

Slides  may  be  cleaned  by  breathing  on  them  While  cold, 
polishing  quickly  afterward,  or  by  washing  with  wood  alcohol 
and  polishing. 

Another  essential  to  good  stereopticon  projection  is  per- 
fect steadiness  of  the  picture  on  the  screen.  Providing  the 
operating  room  floor  be  solid  and  the  machine  properly 


Figure  296. 

anchored,  there  is  ordinarily  no  lack  of  steadiness  of  the 
picture  where  a  dissolver  is  used,  but  when  using  a  single 
lamp,  with  a  double  slide  carrier,  many  operators  will  move 
the  carrier  more  or  less  in  process  of  taking  out  and  putting 
in  a  slide.  This,  of  course,  causes  the  slide  in  the  other 
compartment  of  the  carrier  to  move,  and,  as  it  is  being  pro- 
jected at  the  time,  it  of  course  follows  that  the  picture  on 
the  screen  also  moves.  What  a  truly  absurd  effect  is  pro- 
duced when  one  is  watching,  for  instance,  the  projection  of 
a  picture  of  a  city  and,  due  to  the  ignorance  or  carelessness 


FOR   MANAGERS   AND    OPERATORS  611 

of  the  operator,  the  city  suddenly  jumps  up  into  the  air  a 
couple  of  feet  and  settles  back  with  a  slam! 

When  using  a  double  carrier  be  very  careful  in  removing 
and  inserting  slides.  This,  like  many  other  things,  is  very 
easy  of  accomplishment  if  you  know  how.  There  is  a  right 
and  a  wrong  way  to  do  everything,  even  the  putting  in  and 
taking  out  of  slides.  With  the  thumb  and  forefinger,  grasp  the 
slide  by  the  upper  corner  nearest  to  you.  Insert  its  lower 
edge  gently  into  the  carrier,  and,  as  it  drops  down,  catch 
it  with  the  large  finger  of  the  same  hand,  holding  the  finger 
against  the  slide  and  the  bar  of  the  carrier,  which  will  allow 
you  to  ease  it  down  carefully  into  position  without  in  the 
least  jarring  the  carrier.  The  method  of  doing  this  is  illus- 
trated in  Fig.  296.  This  has  the  additional  advantage  that 
in  removing  and  inserting  slides  you  don't  get  your  fingers 
smeared  all  over  their  surface.  The  finger  only  touches 
the  slide  on  the  surface  which  is  covered  by  the  mat,  hence 
if  you  learn  to  handle  your  slides  this  way  there  will  be  no 
fingermarks  to  show  on  the  screen. 

In  Fig.  295  we  see  a  picture  of  the  mat  side  of  an  adver- 
tising slide.  In  the  lower  left-hand  corner  you  will  observe 
a  black  mark.  This  mark  should  be  present  in  one  corner 
or  the  other  of  all  slides.  It  is  designed  to  enable  the 
operator  to  get  his  slides  piled  up  and  in  the  carrier  cor- 
rectly. In  this  instance  the  mat  side  of  the  slide  is  shown, 
which  would  go  next  to  the  light,  and  the  mark,  being  on 
the  lower  left-hand  corner,  would  be  in  the  upper  corner 
next  to  the  operator  as  he  puts  the  slides  into  the  carrier. 
This  mark  may  be  a  round  dot,  a  star  or  a  small  paper  label.  The 
point  is  that  it  should  always  be  in  the  same  corner  of  all 
slides  of  any  one  set,  so  that  in  laying  your  slides  out  for 
use  you  merely  pile  them  mat  side  up  with  the  mark  of  all 
slides  in  the  same  relative  position. 

Caution:  This  cannot  always  be  absolutely  depended  on,  and 
should  be  checked  up  by  the  operator  after  piling  the  slides, 
since  occasionally  an  error  is  made  by  the  girls  who  bind 
the  slides  up,  and  one  of  the  marks  may  be  in  the  wrong 
corner. 

There  is  absolutely  no  excuse  whatever  for  an  operator  get- 
ting a  slide  in  the  carrier  wrong  side  up. 

Such  a  thing  can  only  be  the  result  of  rank  carelessness  or 
inexperience.  When  running  song  slides  the  operator  who 
knows  his  business  proceeds  as  follows:  On  receipt  of  a 
set  of  song  slides,  he  first  cleans  them  thoroughly.  He  then 
lays  them  in  order,  mat  side  down,  beginning  with  the  title 


612  MOTION    PICTURE    HANDBOOK 

and,  1,  2,  3,  4,  5,  etc.,  until  the  chorus  slide  is  reached,  being 
sure  that  the  spot-mark  of  all  slides  is  in  the  same  corner. 
He  now  turns  the  whole  pile  over  and  runs  through  them, 
glancing  at  scenes  to  check  up  the  spot-mark,  and  to  see 
that  the  tops  of  all  slides  are  in  the  same  position.  He  then 
lays  the  pile  of  slides  on  the  machine  table  with  the  top  of 
the  scenes  toward  the  lamphouse.  In  running  them  he  picks 
each  slide  up  by  the  right-hand  corner  nearest  to  him.  He 
will  thus  be  grasping  the  lower  left-hand  corner  of  the  slide, 
which  will  be  the  upper  right-hand  corner  as  it  goes  into 
the  carrier  in  an  inverted  position.  In  removing  the  slide 
from  the  carrier  he  will  lay  it  down  with  what  was  the  top 
edge  of  the  slide,  as  it  stood  in  the  carrier,  toward  the  lamp- 
house.  Follow  the  directions  through  carefully  and  you  will 
discover  that  he  has  simply  turned  the  slide  over  in  the 
process,  and  as  he  takes  them  out,  one  by  one,  and  thus  lays 
them  down  he  will  have  their  order  exactly  reversed  in  re- 
lation to  the  way  they  originally  laid,  so  that  the  title  will 
be  on  the  bottom,  and  the  top  of  the  slide  away  from  the 
lamphouse.  Under  these  conditions,  when  a  song  is  finished 
all  you  have  to  do  is  to  turn  the  whole  pile  over  and  they 
are  ready  to  run  again. 

The  operator  who  follows  these  directions  closely  will 
never  get  a  slide  in  bottom  side  up.  In  a  short  while  the 
whole  thing  becomes  a  semi-automatic  performance,  and  he 
would  no  more  dream  of  picking  up  a  slide  and  putting  it  in 
the  carrier  and  taking  it  out  and  laying  it  down  in  any  other 
way  than  as  before  indicated  than  he  would  think  of  putting 
a  spoonful  of  food  in  his  ear  instead  of  his  mouth. 

In  event  a  slide  becomes  cracked,  it  may  be  made  as  good 
as  new  if  the  crack  is  in  the  cover-glass — remembering  that 
the  cover-glass  is  always  on  the  mat  side  of  a  slide.  In  that 
event  all  one  has  to  do  is  remove  the  broken  cover-glass 
and  put  in  a  perfectly  clean,  new  one,  rebinding  the  slide  as 
it  was  before.  If,  however,  the  crack  is  in  the  photograph 
the  damage  is  past  remedying.  Gummed  slide  binding  tape 
may  be  had  from  any  exchange,  and  should  be  a  part  of  the 
equipment  of  every  operating  room. 

Advertising  Slides. — It  is  quite  possible  and  practical  to 
make  slides  designed  to  convey  various  messages  to  the 
audience,  and  many  are  the  schemes  which  have  been  evolved 
for  this  purpose.  The  highest  grade  slides  of  this  character 
are,  of  course,  made  by  photography.  The  most  satisfactory 
photographic  slide  is  made  by  lettering  a  black  card  with 
white  paint.  Any  size  card  from  6  by  8  inches  up  to  2  feet 


FOR    MANAGERS   AND    OPERATORS  613 

wide  will  do.  Any  desired  photograph  may  be  attached  to 
the  card  together  with  the  lettering.  The  white  paint  is 
made  of  dry  white  lead  and  thin  glue  mixed  thick  enough  to 
be  easily  applied  but  not  thin  enough  to  run.  Being  sup- 
plied with  the  advertising  text  matter  any  sign  painter  can 
make  the  card,  or  with  practice  even  theatre  managers 
may  learn  to  do  this  fairly  well,  particularly  if  they  secure 
books  of  architects'  alphabets  to  use  as  a  guide.  A  card 
should  be  printed  in  the  proportions  of  3^4  by  4  inches — that 
is  to  say,  it  may  be  any  size,  but  in  those  proportions.  Hav- 
ing finished  the  card,  it  is  then  photographed  in  the  usual 
manner,  and  the  positive  print  made,  either  by  reduction  or 
by  contact  if  the  negative  is  of  slide  size.  In  making  up 
the  card  don't  try  to  get  too  much  reading  matter  in  the 
allotted  space,  because  the  slide  will  only  be  projected  for  a 
few  seconds,  and  if  it  is  too  long  the  audience  will  be  unable 
to  read  it  in  full.  Also  too  much  ornamentation  is  a  detri- 
ment, the  plain  slide  being  more  pleasing  and  understandable 
than  one  containing  an  excess  of  "gingerbread."  In  making 
a  slide  it  must  be  remembered  that,  whereas  the  slide  itself 
is  3J4  or  4  inches  the  mat  opening  is  only  2^4  by  3  inches, 
so  that  the  positive  print  must  include  all  lettering  within 
a  little  less  than  these  last  named  dimensions.  Those  who 
have  made  slidemaking  a  business  say  that  for  making  the 
negative  the  regular  slide  plate  is  most  satisfactory,  and 
Defender,  grade  A,  is  pronounced  excellent.  For  the  devel- 
opment of  the  Defender,  grade  A,  the  following  formula  is 
given  by  Burton  H.  Allbee: 

A:  Water  10  ounces 

Hydroquinone    75  grains 

Potassium    metabisulphite 5  grains 

Potassium    bromide 25  grains 

B :  Water 10  ounces 

Sodium   sulphite 1  ounce 

Caustic  potash 50  grains 

If  a  slide  size  negative  is  used,  the  slide  positive  should 
be  printed  by  contact.  It  is  recommended  that  the  exposure  be  five 
seconds  at  a  distance  of  3  feet,  using  ,a  sixteen-candle  power 
carbon  lamp.  Development  s'hould  be  the  same  as  for  the 
negative. 

If  only  one  copy  of  a  slide  is  desired,  it  may  be  made  by 
writing  on  a  white  card  with  perfectly  black  ink,  reversing 
the  plate  in  the  holder  and  stopping  the  lens  down  to  make 
up  for  focus  thrown  out  by  reversal  of  the  slide,  and  ex- 


614  MOTION    PICTURE   HANDBOOK 

posing.  The  slide  will  then  develop  white  letters  on  a  black 
background  and  be  ready  for  finishing,  the  same  as  a  contact 
slide  from  negative.  It  is  also  possible  to  write  on  trans- 
parent celluloid  with  India  ink  and  print  by  contact.  This 
latter  method  has  the  advantage  of  saving  expense  of  slide 
plate  negative,  and  the  celluloid  costs  very  little  and  may 
be  used  over  and  over  again,  since  the  ink  can  be  washed 
off.  In  general  it  may  be  said  that  black  background  slides 
are  more  pleasing  than  those  with  white  backgrounds,  since 
the  glare  from  a  white  background  is  hard  on  the  eyes,  and 
makes  the  slide  comparatively  difficult  to  read.  When  a 
slide  has  been  washed  and  fixed  it  should  be  set  to  dry,  and 
should  not  be  moved  during  the  drying  process,  since  mov- 
ing it  will  cause  uneven  density. 

Coloring. — When  the  positive  print  is  finished  it  may  be 
colored  if  desired,  the  operation  being  very  simple.  Velox 
water  colors  are  perhaps  best,  and  a  single  sheet  will  color 
many  slides,  therefore  the  cost  is  but  slight.  One  stamp 
dissolved  in  two  ounces  of  water  will  make  about  the  right 
color  strength,  and  once  made  it  can  be  bottled  up  for 
future  use.  A  number  10  brush  is  about  right  for  every- 
thing except  for  very  small  letters.  If  the  background  of 
the  slide  is  black  the  color  may  simply  be  flowed  all  over 
the  letters  and  background.  Red,  yellow,  and  either  green 
or  purple  are  most  satisfactory  for  printed  slides,  some 
letters  being  left  white.  Don't  have  all  the  color  in  one 
place  as,  for  instance,  red  at  the  top,  yellow  in  the  middle, 
and  green  at  the  bottom.  A  more  pleasing  effect  is  had  by 
dividing  the  colors  up  more,  but  experience  in  this  matter 
is  the  best  teacher.  Flow  the  color  over  the  letters,  let  it 
stay  a  moment,  afterward  removing  the  surplus  water  with 
a  dry  brush,  and  the  letters  will  be  evenly  colored.  If  the 
shade  is  not  dark  enough  repeat  the  operation  until  it  is. 
After  coloring  don't  wash  the  slide  but  set  it  to  dry,  turn- 
ing it  occasionally  to  maintain  evenness  of  the  coloring. 
After  the  coloring  is  completed  the  slide  may  be  bound  up 
in  the  usual  way,  being  sure,  however,  to  have  your  cover 
glasses  clean  on  the  inside. 

There  are  also  on  the  market  a  number  of  paints  with 
which  a  slide  cover  glass  may  Le  coated,  and  when  dry,  any 
message  it  is  desired  to  present  to  the  audience  may  be  writ- 
ten on  this  coating  with  a  stylrs  or  other  blunt  instrument. 
The  effect  is  letters  of  light  on  an  opaque  background. 

It  is  entirely  practical  to  write  on  gelatine  either  with 
typewriter  or  India  ink  or  by  means  of  carbon  paper,  and  if 


FOR   MANAGERS  AND    OPERATORS 


615 


properly  done  a  reasonably  sharp  and  fairly  good  slide  is 
produced,  though  of  course  it  does  not  compare  with  the 
photographic  slide.  In  addition  to  this,  colored  inks  are 
produced  with  which  one  can  write  on  clear  glass,  using  an 
ordinary  pen.  If  carefully  made,  slides  of  this  kind  present 
a  pleasing  appearance,  and  they  have  the  advantage  of  being 
cheaply  and  quickly  made.  "Glassine,"  made  by  the  Thad- 
deus  Davids  Company,  New  York,  is  such  an  ink.  It  comes 
in  several  colors  and  is  excellent. 

Slide  Coatings. — Dissolve  dry  gum  dammar  in  turpentine 
and  allow  to  stand  until  it  settles.  The  proportion,  by 
measure,  is  about  one  of  dry  dammar  to  twenty  of  turpen- 
tine. Very  thin,  yes,  but  it  does  the  trick.  To  coat  hold  a 
clean  cover  glass  level,  pour  on  some  solution,  allowing 
it  to  spread  over  the  entire  surface.  Then  allow  the  surplus 
to  drain  back  into  the  bottle  from  one  corner,  and  stand 
the  glass  on  end  to  dry.  Glass  treated  thus  may  be  written 
on  with  an  ordinary  pen  and  ink  just  as  one  would  write 
on  paper.  It  will  require  several  jtioars  to  dry,  but  the  writ- 
ing may  be  washed  off  with  turpentine  and  the  coating  used 
many  times.  It  is  difficult  to  tell  wLich  is  the  coated  side. 
Therefore  a  small  gummed  sticker  should  be  affixed  in  one 
corner  or  a  permanent  mark  made  with  ink.  Gelatine  may 
also  be  used  for  coating,  the  process  being  as  above,  sub- 
stituting for  the  dammar  coating  one  made  by  dissolving 
in  :hot  water  clear  gela- 
tine, which  can  be  had 
from  any  grocery  or 
drug  store,  in  propor- 
tion of  one  measure  of 
gelatine  to  ten  of  water. 
This  coating  is  fairly 
satisfactory,  but  can 
only  be  used  once.  The 
solution  should  be  pass- 
ed through  filter  paper 
before  using,  or  at  least 
be  strained  through 
very  fine  cloth. 

Those   making   many  Figure  297. 

slides  of  this  kind  will 

find  the  following  a  great  help:  Get  a  board,  either  bass- 
wood  or  clear,  soft  pine,  of  convenient  size,  say  12  inches 
square.  On  one  surface  paste  a  sheet  of  white  paper,  six  or 
eight  inches  square,  and  on  this  paper  paste  an  ordinary 


616  MOTION    PICTURE   HANDBOOK 

slide  mat,  laying  off  the  paper  surface  inside  the  mat  checker- 
board fashion  with  the  lines  about  three-sixteenths  of  an  inch 
apart  both  ways,  as  per  Fig.  297.  In  practice  lay  the  glass 
upon,  which  you  propose  to  write  over  the  slide  mat,  fasten- 
ing it  in  place  with  draughtsmen's  thumb  tacks  (10  cents  a 
box,  at  hardware  or  drug  stores  in  small  towns).  The  lines 
will  serve  as  a  guide  for  your  writing  and  enable  you  to  do 
a  neat  job.  You  may  use'black  or  colored  inks.  Clean  glass, 
over  which  the  tongue  has  been  passed,  may  be  written  on 
after  the  saliva  deposit  has  dried. 

Comic  or  other  newspaper  pictures  may  be  transferred  to 
clean  cover  glass  by  laying  a  sheet  of  good  heavy  carbon 
paper  face  downward  on  the  glass,  the  picture  on  top  of  the 
carbon  paper,  and  tracing  the  outlines  with  a  stylus  or  even 
with  a  smooth-pointed,  rather  hard  lead  pencil.  If  good 
carbon  paper  is  used  and  the  tracing  neatly  done  the  effect 
is  not  at  all  bad,  though  it  is  better  if  a  dammar  or  gelatine 
coated  glass  be  used.  Colored  gelatine  paper  may  be  used 
to  tint  such  slides  with  good  effect.  Just  bind  the  tint  of 
gelatine  you  prefer  between  the  drawing  and  a  clean  cover 
glass,  using  gummed  binder  strip  to  hold  the  glasses  to- 
gether. Even  smoked  glass  may  be  employed  for  slides  which 
are  to  be  used  only  once,  though  the  effect  is  seldom  satis- 
factory, because  it  is  almost  impossible  to  write  the  text 
and  get  the  glass  into  the  slide  carrier  without  marring  the 
smoked  surface.  Just  smoke  the  glass  in  a  candle  flame, 
or  the  flame  of  a  match,  and  write  in  the  smoke  with  any 
sharp-pointed  instrument.  A  lead  pencil  will  do  very  well. 
Newspaper  pictures  or  text  may  be  transferred  to  glass  as 
follows:  Coat  one  side  of  perfectly  clean  cover  glass  with 
coach  varnish.  Let  stand  until  it  is  "tacky."  Lay  the  matter 
to  be  transferred  face  down  on  varnish  and  rub  with  bowl  of 
table  spoon,  from  center  out,  until  all  air  bubbles  have  dis- 
appeared. Let  lay  24  hours,  then  soak  in  water  thoroughly 
and  carefully  rub  the  paper  off  with  the  finger.  The  ink 
will  remain. 

A  whole  book  could  be  written  on  stereopticon  projection, 
but  I  do  not  feel  justified  in  devoting  more  space  to  this 
subject,  because  of  the  fact  that  there  is  comparatively  now 
but  little  stereopticon  projection  being  done  in  moving 
picture  theatres. 


FOR    MANAGERS   AND    OPERATORS  617 

Operator's  License 

IN  many  localities  theatre  managers  have  opposed  the 
license  law,  although  it  has  been  almost  universally 
welcomed  by  operators.  In  fact,  in  many  cases  oper- 
ators' unions  have  helped  secure  the  passage  of  license  laws. 
A  license  law,  always  provided  it  be  drafted  along  the  lines 
of  common  sense  and  the  examination  of  operators  be  con- 
ducted by  men  who  have  at  least  a  fair  working  knowledge 
of  projection  and  the  things  allied  thereto,  is  a  good  propo- 
sition, both  from  the  managers'  and  operators'  point  of 
view.  A  license  law  rightly  and  properly  carried  out  will 
have  a  decided  tendency  to  eliminate  the  incompetent  and 
to  improve  conditions  in  general.  It  is  a  mistake  to  sup- 
pose that  a  license  law  has  the  effect  of  curtailing  the  sup- 
ply. Take  Massachusetts,  for  example;  there  is  a  license 
law,  backed  up  by  a  pretty  stiff  examination,  yet,  as  a 
matter  of  fact,  notwithstanding  the  stiff  examination,  there 
are  operators  far  in  excess  of  the  demand  in  that  state. 
However,  according  to  the  statement  of  Massachusetts'  of- 
ficials, whereas  the  license  law  has  not  operated  to  curtail  the 
supply,  it  has  operated  to  raise  the  efficiency  of  the  operators 
very  materially. 

But  even  assuming  that  a  good,  stiff  examination  would 
tend  to  decrease  the  supply  and  raise  salaries  (not  a  fact, 
but  merely  an  assumption  for  the  sake  of  argument)  it  is  a 
fact  now  quite  generally  accepted  by  the  better  class  of 
managers  that  cheapness  in  operators'  salaries  is  not  a  good 
business  proposition.  Very  many  high-class  managers  now 
thoroughly  understand  that  it  is  quite  possible  to  save  one 
dollar  in  operator's  salary  and  lose  three  in  box  office  receipts 
in  the  process.  The  employment  of  incompetent  operators, 
usually  tolerated  because  they  are  cheap,  acts  not  only  to 
injure  results  on  the  screen  and  thus  lessen  the  pleasure  of 
the  great  mass  of  moving  picture  patrons,  but  it  also  adds  an 
element  of  danger.  In  fact,  the  public  in  general  have,  large- 
ly by  reason  of  scarehead  newspaper  articles,  not  only  be- 
come aware  of  the  highly  inflammable  nature  of  film,  but 
have  received  a  grossly  exaggerated  idea  of  the  danger  in 
moving  picture  theatres.  Therefore,  under  this  condition, 
the  operator  has  become  in  a  sense  the  guardian  of  the 
safety  of  his  audience — a  responsibility  he  ought  thoroughly 
to  realize,  since,  should  he  by  any  careless  act  ignite  the 
film,  while  it  is  highly  improbable  that  the  resultant  fire 
would  in  any  way  endanger  life  or  even  work  the  slightest 


618  MOTION    PICTURE   HANDBOOK 

injury  to  any  one  of  the  audience,  still  might  be  the  cause 
of  a  panic,  and  the  result  of  a  panic  no  man  can  forsee. 

It  is  this  danger  which  has  brought  about  the  licensing  of 
operators,  and  the  licensing  power  is  vitally  interested  in  the 
safety  of  the  public,  and,  as  a  general  proposition,  examina- 
tions are  largely  conducted  with  the  idea  of  ascertaining  the 
competency  of  the  operator  from  the  fire-danger  point  of 
view  only. 

This,  however,  is  an  error,  since  the  public  is,  and  there- 
fore the  licensing  power  ought  to  be  vitally  interested  in  the 
competency  of  the  operator  from  the  projection  point  of 
view,  since  the  competent  operator  can  keep  his  machine 
adjusted  and  in  such  repair  that  there  will  be  a  minimum  of 
movement  in  the  picture  upon  the  screen;  he  can  keep  his 
picture  in  sharp  focus  upon  the  screen,  and  he  can  fit  his 
revolving  shutter  to  meet  the  local  conditions,  thus  reducing 
flicker  to  a  minimum.  And  all  these  various  things  have  to  do 
with  eyestrain.  Therefore,  in  the  judgment  of  the  author,  the 
licensing  authorities  should  see  to  it  that  the  operator  is  not  only 
a  safe  man  from  the  fire  standpoint,  but  that  he  is  also 
competent  from  the  projectional  point  of  view. 

As  a  matter  of  fact,  if  the  newspaper,  instead  of  publish- 
ing ridiculous  stories  about  fire  danger  would  inform  its 
readers  that  in  the  modern  moving  picture  theatre  the  operating 
room  is  thoroughly  fire-proof  and  that  there  is  absolutely 
no  danger  whatever  to  the  audience  from  a  film  fire  in  the 
operating  room,  the  danger  of  panic  (the  only  danger  there 
is)  would  very  soon  be  largely  reduced.  I  make  the  broad 
statement  that  the  newspapers  themselves  are  largely  re- 
sponsible for  the  injury  and  death  resulting  from  moving 
picture  theatre  fire  panics. 

I  do  not  wish  to  be  understood  as  intimating  that  the  opera- 
tor should  not  be  thoroughly  examined  as  to  his  ability  as 
applied  to  fire-danger.  Laying  aside  the  danger  to  the  audi- 
ence, the  operator  is  placed  in  charge  of  valuable  property 
within  the  operating  room,  which  may  be  damaged  or  en- 
tirely destroyed  by  fire.  Therefore,  from  any  and  every  point 
of  view  he  should  be  a  man  thoroughly  competent  to  handle 
operating  room  equipment. 

I  mention  these  things  broadly,  and  might  add  that  even  the 
operator  who  is  thoroughly  competent,  so  far  as  knowledge  goes, 
may  be  thoroughly  incompetent  by  reason  of  the  fact  that  he  is 
shiftless  and  lazy.  But  the  fact  remains  that  the  competent  man 
can  be  compelled  to  do  his  work  right,  whereas  the  cheap, 


FOR    MANAGERS    AND    OPERATORS  619 

incompetent  man  cannot  be  compelled  to  do  his  work  right, 
because  he  doesn't  know  how. 

The  licensing  of  operators  always  tends  to  increase  their 
efficiency  because  they  must  pass  an  examination,  which 
compels  them  to  study,  at  least  to  some  extent,  and  the 
knowledge  thus  acquired  they  would  not  otherwise  in  all 
human  probability  possess. 

The  theatre  manager  who  is  a  real  manager  will  welcome 
anything  which  tends  to  raise  the  efficiency  of  operators, 
because  it  is  upon  that  efficiency  he  must  depend  for  results 
upon  his  screen.  The  real  manager  will  even  welcome  in- 
creased efficiency  at  a  higher  price,  and  the  other  kind  ought 
to  be  compelled,  if  necessary,  to  pay  the  price  for  excellence 
in  projection. 

The  author  of  this  book  is  heartily,  thoroughly,  and  com- 
pletely in  accord  with  the  examination  and  licensing  of 
operators,  but  he  suggests  that  the  examining  board  which 
issues  licenses  be  composed  or  partly  composed  of  men  who 
have  at  least  a  fair  working  knowledge  of  practical  projec- 
tion. The  fact  that  a  man  occupies  a  position  as  head  of  a  city 
department  is  no  proof  that  he  is  a  competent  examiner  for 
moving  picture  operators,  any  more  than  he  would  be  a  competent 
examiner  for  locomotive  engineers  or  sea  captains. 

It  is  hard  to  say  just  what  the  make-up  of  the  examiners' 
board  should  be,  but  as  a  general  proposition,  in  the  judg- 
ment of  the  author,  the  board  should  be  composed  of  (a)  one 
thoroughly  competent,  practical  electrician;  (b)  the  head  of 
the  building  or  fire  inspection  department;  (c)  one  man 
thoroughly  acquainted  with  practical  projection  and  operating 
room  practice — in.  other  words,  an  operator. 

It  would  be  just  as  well  to  have  the  board  composed  of  only 
one  man,  if  the  right  man  could  be  found,  but  he  would 
have  to  be  thoroughly  versed  in  practical  projection  and 
operating  room  practice,  a  thorough  electrician,  and  should 
have  complete  knowledge  of  the  construction  of  operating 
rooms  and  their  ventilation. 

The  best  operators'  examination  of  which  I  have  personal 
knowledge  is  that  conducted  in  Massachusetts  by  the  De- 
partment of  District  Police,  State  House,  Boston.  For  five 
years  Mr.  Harry  Atkinson,  State  Building*  Inspector,  had 
charge  of  examinations.  Mr.  Atkinson  has  made  a  close 
study  of  the  points  involved  in  practical  projection,  and  is 
now,  I  believe,  a  thoroughly  practical  and  absolutely  compe- 
tent examiner — I  know  of  none  more  so.  For  some  time, 
however,  the  examinations  have  been  in  charge  of  State 


620  MOTION    PICTURE   HANDBOOK 

Building  Inspector  Ryan,  who  also  is  thoroughly  versed  on 
points  pertaining  to  practical  projection,  including  electrics, 
operating1  room  construction,  ventilation  of  the  operating 
room,  the  mechanics  of  the  projector,  and  the  optical  end 
of  the  projector,  particularly  as  applied  to  the  revolving 
shutter.  Of  late  the  New  York  City  Board  has  been  doing 
good  work,  under  Chief  Examiner  Brown.  These  two  boards 
are  the  best  of  which  I  have  present  personal  knowledge. 
The  examination  of  operators  should  seek  to  determine 

(a)  ability  to  measure  wires  and  calculate  their  capacities; 

(b)  extent  of  understanding  of  electrical  action  as  applied  to 
the  ordinary  multiple  arc  and  three-wire  system;   (c)  extent 
of  knowledge  of  the  principles  involved  in  the  transformers; 
(f)  knowledge  of  motors  and  generators,  particularly  as  ap- 
plied to  the  care  of  the  commutator  bearings  and  the  testing 
for  electrical  faults,  such   as  grounded  armature  coils,  loose 
joints  in  the  magnetic  circuit,  this  because  more  and  more 
operators  are  being  called  upon  to  operate  motor  driven  ma- 
chines  and   motor   generator   sets;    (g)    knowledge    of   the 
principles  involved  in  the  mercury  are  rectifier;   (h)  knowl- 
edge of  fusing;  (i)  knowledge  of  rheostat  resistance  and  its 
application  to  the  projection  circuit;   (j)   the  effect  of  over- 
loading the   wires;    (k)    knowledge  of  the  various  points  in 
operating    room    construction    and    equipment,    particularly 
with   regard   to   the   fuse   system    of   the   port   fire    shutter; 
(1)  knowledge  of  the  motion  picture  mechanism  and  of  the 
arc  lamp;    (m)   knowledge   of  film,,  including  how  to  make 
a  proper,  straight,  smooth  splice,  the  effect  of  worn  sprocket 
teeth  on  the  film  and  on  the  projected  picture,  the  effect  of 
worn  aperture  plate  and  other  worn  parts  of  the  mechanism 
on  projection;   (n)  knowledge  of  optical  principles  involved 
in   the    revolving   shutter   of   the   mechanism,   including  the 
knowledge  of  how  to   make   the  projector   shutter   fit  local 
conditions  as  nearly  as  possible,  thus  reducing  flicker  to  a 
minimum,  and   such   other  things   as   may  occur  to  the   ex- 
aminers, including  the  cause  of  damage  to  film  in  rewinding, 
and  how  to  minimize  its  effect. 

Up  to  date  the  worst  trouble  with  the  licensing  proposi- 
tion lies  in  the  almost  universal  weakness  of  examining 
boards,  and  in  many  cases  their  total,  absolute  incompetency.  It 
savors  of  highway  robbery  to  compel  an  operator  to  pay  a 
fee  for  a  license  where  the  examination  is  nothing  more 
or  less  than  a  farce,  yet  I  am  obliged  to  say  that— from  the 
evidence  in  hand — this  is  the  situation  in  some  of  the  smaller 
cities,  as  well  as  in  a  number  of  the  larger  ones. 


FOR    MANAGERS   AND    OPERATORS  621 

Rough  Draft  of  License  Law. — It  would  be  impractical  to 
include  a  model  operators'  license  law  in  this  book,  because 
of  the  difficulty  in  framing  a  law  which  in  all  its  details 
would  be  applicable  to  varying  local  conditions.  The  fund- 
amental principles  of  such  a  law,  however,  would  be  the 
same  in  any  locality,  and  it  is  these  fundamental  principles  I 
propose  to  incorporate,  leaving  the  suggested  details  to  be 
worked  out  to  fit  individual  local  needs. 

(1)  Designate  places  in  which  it  shall  be   illegal  to  dis- 
play motion  picture  films  until  the  projecting  apparatus  and 
the  operating  room  have  been  approved  and  duly  licensed. 
Forbid  the  use  of  oxyhydrogen  gas  or  limelight  for  motion 
picture   projection.     Name   the   licensing  power  .and   give   it 
authority  to  make  regulations  and  to  enforce  them. 

(2)  Provide    for    an    examination    for    operator's    license. 
Specify   briefly  the   qualifications   necessary  to   obtain   such 
license.     Require  that  the  applicant  for  license  shall  have  a 
certain  amount  of  experience,  either  as  an  operator  or  opera- 
tor's assistant  to  be  eligible  for  an  examination.     Establish 
minimum  age  of  an  operator  (twenty-one  years). 

(3)  Provide   for   the    licensing   of    persons   to   act    as    as- 
sistants to  operators,  and  designate  what  work  in  the  opera- 
ting room  they  may  and  what  they  shall  not  do.     Minimum  age 
to  be  one  year  less  than  for  operator. 

(4)  Provide  for  fees  to  be  paid  for  the  licensing  of  ma- 
chine, operating  room,  operator  and  assistant  operator,  also 
for  annual  renewal  of  the  two  last  mentioned  licenses,  and 
fee  for  the  same. 

(5)  Provide   penalties   for  violation   of  any  provision   of 
law  or  regulation  of  the  licensing  authority. 

In  addition  to  these  general  provisions  I  would  suggest 
that  the  law  governing  operating  rooms  should  make  pro- 
vision for  (a)  their  thorough  ventilation;  (b)  a  vent  flue 
sufficiently  large  to  carry  away  all  fumes  and  smoke  in  case 
of  film  fire  and  to  contain  an  electric  fan  of  ample  dimen- 
sions; (c)  a  fire  shutter  fusible  link  system  along  the  lines 
suggested  on  Page  223;  (d)  that  placing  conduit  on  the  floor 
should  be  forbidden;  (e)  that  the  operating  room  construction 
should  be  such  that  its  walls  will  be  thoroughly  fire-proof, 
and  that  brick,  hollow  tile,  or  concrete  be  required  where  its 
use  is  practical;  (f)  that  the  operating  room  feed  wires  be 
large  enough  to  carry  the  combined  current  capacity  of  all 
apparatus  in  the  operating  room,  regardless  of  whether  it  i 
ever  all  used  at  one  time  or  not;  (g)  that  it  be  required  tha 
the  wiring  be  so  done  that  the  operator  will  in  case  of  nee 


622  MOTION    PICTURE   HANDBOOK 

be  able  instantly  to  switch  on  a  portion  of  the  house  lights; 
(h)  that  a  metal  receptacle  for  hot  carbon  butts  be  required; 
(i)  that  all  film  rewinding  and  repairing  be  done  either  in- 
side the  operating  room  or  in  a  fire-proof  room  immediately 
adjoining  and  connecting  thereto;  (j)  that  proper  fire-proof 
metal  receptacles  be  required  for  films,  and  that  it  be  re- 
quired that  all  film  not  in  actual  use  or  in  process  of  repair 
or  rewinding  be  at  all  times  kept  in  these  receptacles;  (k) 
that  metal  lining  of  operating  rooms  be  forbidden;  (1)  that 
the  projection  machine  be  thoroughly  grounded  to  the  metal 
lining  or  framework  of  the  operating  room,  if  there  is  such; 
(m)  that  the  keeping  of  oils,  alcohol  or  highly  inflammable 
substances  in  quantities  of  more  than  two  ounces  each  be 
forbidden;  (n)  that  no  exposed  inflammable  material  be 
allowed  inside  the  operating  room,  except  a  work  bench  of 
two-inch  hard-wood  lumber,  and  such  other  regulations  as 
may  seem  advisable. 

Operator's  Report 

ONE  of  the  things  which  would  very  largely  tend  to 
remedy  the  matter  of  poor  inspection  in  exchanges 
would  be  an  operator's  report  blank,  which  theatres 
ought  to  have  printed  and  require  their  operators  to  make 
out,  the  same  to  be  forwarded  to  the  manager  of  the  exchange 
with  the  weekly  check.  These  reports  should  not  be  sent  in 
with  the  films,  thus  falling  into  the  hands  of  subordinates  and 
probably  either  disregarded  or  destroyed.  The  manager  of 
the  exchange  is  the  man  who  should  get  them.  If  reports  such 
as  these  are  made  out  and  retained,  when  the  theatre  manager 
comes  to  send  in  his  check  he  is  in  position  to  comment  in- 
telligently upon  the  condition  of  the  service. 

With  this  end  in  view  I  submit  what  I  believe  to  be  a 
fairly  good  blank  form  for  this  purpose. 

A  blank  of  this  kind  not  only  will  enable  the  manager  to 
check  up  on  the  condition  of  his  service,  but  will  also  place 
the  exchange  manager  in  position  to  check  up  the  work  of 
his  inspection  department.  If  it  is  found  that  the  films  are 
chronically  in  bad  condition,  then  these  reports  should  be 
sent  directly  to  the  head  office  of  the  General  Film,  the 
Universal,  Mutual  or  whatever  the  service  is,  with  the  sug- 
gestion that  an  inquiry  be  made  of  the  exchange  manager 
as  to  the  reason  for  the  condition  of  his  films. 

When  a  film  is  re-csived  in  bad  condition  it  is  well  to  send 
in  the  inspection  tag.  if  one  there  be,  together  with  the  opera- 


FOR   MANAGERS   AND    OPERATORS  623 

tor's  report.    This  enables  the  exchange  manager  to  fix  the 
blame  directly  on  the  inspector  responsible. 


OPERATOR'S  REPORT. 

HO Date    

Condition  of  ?ilm  Received  from * t. . . . 

Heel  No 

Name  of  Subject  

I 
Leader  

Title  

End  

Irregular  Splices  and  Out  of  Frames  

Loose  Patches •  ...•» 

Breaks  in  Film  When  Received , 

Pewounrf   before    Shipped  Away    

Genera]    Condition   Remarks 

Operator. 


Note.— Operator  is  required  to  fill  out  this  blank  completely,  making 
one  copy  to  be  retained  in  the  operating  room,  the  original  to  be 
delivered  to  the  theatre  manager. 

Figure  298. 


624  MOTION    PICTURE   HANDBOOK 


Theatre  Heating  and 
Ventilating 

HEATING  and  ventilating  a  theatre  involves  a  consid- 
erable number  of  distinct  and  from  some  points  of 
view  entirely  different  problems.  To  go  into  the 
matter  of  heating  and  ventilating  theatres  with  anything  like 
completeness  would  not  only  consume  a  vast  amount  of  space, 
but  would  necessarily  involve  many  pages  of  highly  technical 
text,  and  there  seems  to  be  no  way  of  avoiding  the  use  of 
technicalities  in  dealing  with  a  matter  of  this  kind.  Not  only 
is  this  true,  but  unless  one  literally  made  a  complete  book  on 
the  subject  I  do  not  believe  the  layman  could  be  taught  to 
apply  the  rules  for  figuring  air  pressure  and  resistance  in 
inches  and  all  that  sort  of  thing  with  any  degree  of  accuracy 
or  success. 

I  shall  therefore  confine  my  remarks  on  these  two  topics 
largely  to  such  things  as  readily  can  be  grasped  and  under- 
stood by  the  average  man.  To  go  further  than  that  is, 
I  think,  not  advisable. 

With  regard  to  ventilation,  there  are,  in  general,  two  dis- 
tinct problems:  First,  how  much  ought  there  to  be;  second, 
which  is  the  better  method  of  heating  for  the  various  parts 
of  the  building,  direct  or  indirect?  The  first  thing  to  do  is 
ascertain  whether  or  not  there  is  a  local  law  on  the  subject 
of  theatre  ventilation,  and  if  there  is  what  are  its  require- 
ments. The  provisions  of  local  law  must,  of  course,  be  com- 
plied with,  but  if  these  provisions  are  insufficient  to  provide 
for  the  comfort  of  the  audience,  then  it  will  be  better  to  go 
beyond  the  local  requirements  and  provide  such  ventilation 
as  will  secure  the  comfort  of  the  audience. 

In  this  connection,  however,  it  should  be  understood  that 
an  atmospheric  condition  which  may  be  entirely  healthful  is 
not  necessarily  such  as  will  produce  comfort.  Healthful  con- 
dition merely  means  the  supplying  of  sufficient  fresh  air  to 
keep  the  vitiated  atmosphere  inside  the  theatre  above  a  cer- 
tain degree  of  impurity.  It  should  also  be  understood  that 
air  will  become  impure  with  a  greater  degree  of  rapidity  in 
summer  time  than  in  winter.  This  is  by  reason  of  the  fact 
that  whereas  in  the  winter  the  air  is  only  laden  with  the 


FOR    MANAGERS   AND    OPERATORS  625 

vitiating  poisons  contained  in  the  exhalations  from  the  lungs 
and  a  comparatively  small  amount  arising  from  the  body,  in  sum- 
mer the  latter  is  very  largely  increased  by  the  rapid  evaporation 
from  the  pores  of  the  skin  and  bodily  heat.  Ventilation  not 
only  includes  the  bringing  in  of  fresh  air  and  the  expulsion  of 
an  equal  amount  of  foul  air,  but  also,  rightly  considered,  in- 
cludes the  control  of  moisture. 

Briefly,  the  feeling  of  comfort  or  coolness  is  largely  if  not 
wholly  a  matter  of  the  rapidity  with  which  evaporation  from 
the  pores  of  the  skin  takes  place.  The  more  rapid  the 
evaporation  from  the  exposed  surfaces  of  the  human  body, 
the  more  comfortable  will  the  individual  feel,  and  as  before 
stated,  it  does  not  follow  that  because  one  feels  comfortable 
the  atmospheric  conditions  are  necessarily  healthful — they 
may  be  far  from  that.  Therefore  ventilation,  as  such,  involves 
the  separate  and  distinct  problems  of  supplying  healthful  con- 
ditions and  comfort. 

It  is  very  generally  conceded  that,  provided  the  outside 
atmosphere  be  itself  reasonably  clean  and  healthful,  the  supply- 
ing of  from  twenty  to  thirty  cubic  feet  of  fresh  air  per  minute 
per  person  is  sufficient  to  produce  reasonably  healthful  con- 
ditions, and  certainly  is  sufficient  to  avoid  any  distress  in 
breathing.  The  actual  necessary  quality  of  fresh  air  is  to 
a  considerable  extent  dependent  upon  the  method  by  which 
it  is  delivered  into  the  room.  In  the  larger  theatres  the 
expensive  but  ideal  practice  is  coming  more  and  more  into 
use  of  delivering  the  intake  of  fresh  air  through  properly 
located  ducts  underneath  the  floor,  which  connect  with  small 
mushroom  ventilators  located  under  each  alternate  or  each 
third  or  fourth  seat,  both  in  the  auditorium  and  in  the  bal- 
cony. This  method  of  distributing  the  intake  assures  a 
thorough  and  even  mixture  of  the  fresh  air  with  the  foul, 
and  where  it  is  employed  it  is  not  necessary  to  supply  air  in 
such  large  volume  as  is  required  where  it  is  brought  in 
through  one,  two,  or  three  or  four  large  openings.  The 
latter  does  not  secure  a  complete  mixture  of  the  fresh  and 
the  foul  air  in  all  portions  of  the  house;  therefore  it  is 
necessary  to  supply  a  larger  quantity.  Briefly  speaking,  I 
think  we  may  say  that  from  fifteen  to  twenty  cubic  feet  of 
air  per  person  per  minute  will  be  entirely  adequate  where 
the  mushroom  system  of  ventilation  is  used,  and  from  twenty- 
five  to  thirty-five  will  answer  where  the  air  is  brought  in 
through  from  one  to  four  large  openings. 

The  methods  employed  for  ventilation  are  many,  but  the 
fan  system  is  the  only  one  upon  which  dependence  may  be 


626  MOTION   PICTURE   HANDBOOK 

placed  for  positive  results.  There  are  those  who  ventilate  by 
means  of  in-lets  located  either  at  the  floor  or  six  feet  above 
it  and  depend  for  the  exhaust  on  one  or  more  large  registers 
in  the  ceiling,  connecting  with  pipes  passing  through  the 
roof  and  terminating  in  a  swinging  cowl  hood. 

This  method  is  not  to  be  recommended.  It  is  at  best  but 
a  makeshift.  There  is  nothing  positive  in  its  action,  and  if 
the  temperature  within  and  without  be  equal  there  will  be  but 
very  little  fresh  air  brought  into  the  auditorium. 

The  fan  system,  on  the  other  hand,  delivers  a  certain 
definite  quantity  of  air  into  the  auditorium,  and  this,  of  course, 
forces  out  an  equal  quantity  of  foul  air,  hence  when  we  use  the 
fan  system  we  know  precisely  how  often  the  air  will  be 
changed  every  minute. 

There  are  those  who  advocate  the  changing  of  the  atmo- 
sphere in  the  auditorium  a  certain  given  number  of  times 
per  hour.  This,  however,  does  not  seem  to  me  to  spell 
common  sense,  because  in  one  theatre  where  the  cubic  con- 
tents are  great  as  compared  to  the  number  of  seats,  it  might 
supply  an  unnecessarily  large  quantity  of  fresh  air,  whereas 
in  another  theatre  where  the  ceiling  is  low  and  the  cubic 
contents  are  very  small,  as  compared  with  the  number  of 
seats,  it  might  fail  to  supply  an  adequate  amount  of  air  to 
keep  the  auditorium  in  healthful  condition.  It  seems  to  me 
that  the  supplying  of  a  certain  number  of  cubic  feet  per  min- 
ute per  seat  is  the  only  proper  basis  to  work  from. 

Wall  and  Ceiling  Fans. — It  will  be  clearly  understood  that 
what  is  known  as  "wall  fans"  and  "ceiling  fans"  have  nothing 
whatever  to  do  with  ventilation,  as  such.  These  fans  are,  how- 
ever, quite  necessary,  and  serve  two  distinct  purposes.  First, 
as  before  said,  anything  which  causes  rapid  evaporation 
frofti  the  pores  of  the  skin  will  produce  a  feeling  of  comfort. 
Now  the  mere  supplying  of  fresh  air  at  the  rate  of  even 
thirty  cubic  feet  per  minute  per  person  may  not  secure  com- 
fort to  the  patron,  because  if  it  is  brought  in  through  mush- 
room ventilators  it  will  practically  not  produce  any  draught 
whatever,  but  simply  produce  a  'healthful  condition,  so  in 
order  to  produce  a  rapid  circulation  and  movement  of  the 
air  we  install  wall  and  ceiling  fans,  and  the  circulation  of  the 
air  by  these  fans  causes  rapid  evaporation  from  the  pores 
of  the  skin,  and  therefore  brings  about  a  feeling  of  comfort, 
and  thus  we  have  the  healthful  condition  through  the  forcipg 
in  of  fresh  air,  and  through  the  stirring  of  it  up  by  the  wall 
and  ceiling  fans  we  get  comfort. 

Very    careful    planning,    judgment    and    care    should    be 


FOR   MANAGERS   AND    OPERATORS  627 

exercised  in  the  location  of  wall  fans.  They  should  not  blow 
directly  on  the  audience,  but  should  be  set  on  shelves  about 
six  or  seven  feet  from  the  floor,  and  set  to  blow  straight 
outward,  pointing  in  the  direction  which  will  assist  rather 
than  retard  the  movement  of  air  through  the  room.  Ceiling 
fans  may,  of  course,  be  located  anywhere  that  is  deemed 
advisable,  since  they  blow  straight  down  and  do  not  ordinarily 
produce  a  strong  current  of  air. 

In  this  connection,  it  is  much  better  to  have  comparatively 
large  wall  fans  running  at  slow  speed,  than  to  have  small 
fans  running  at  high  speed.  They  are  cheaper  of  operation 
and  make  less  noise,  modified  by  the  fact  that  too  large  a 
wall  fan  would  create  too  heavy  an  air  current  in  one  direc- 
tion. What  has  been  said  of  exhaust  fans  applies  equally  to 
wall  fans.  We  may,  however,  consider  18  inches  as  the  ex- 
treme diameter  advisable  to  use.  All  fans  must,  of  course, 
have  intelligent  care  and  attention.  They  should  and  must  be 
oiled  at  stated  periods.  The  bearings  of  electric  fans  have 
an  oil  well.  This  does  not  mean  that  they  will  run  forever 
without  a  refilling  of  the  wells.  The  oil  wells  should  be 
thoroughly  cleaned  out  and  filled  with  fresh  oil  once  a  week 
in  summer.  There  should  be  stated  times  to  do  this,  and  it 
should  be  done  at  that  time,  otherwise  it  will  in  all  human 
probability  be  neglected,  and  this  neglect  will  mean  cut 
journals  and  trouble.  The  commutators  of  fans  should  be 
examined  occasionally  and  both  the  bars  and  bushes  kept  in 
good  condition.  A  good  scheme  with  fan  commutators  is 
to  let  well  enough  alone.  That  is  to  say,  if  the  commutator 
is  running  nicely,  don't  fool  with  it.  If  it  is  sparking  badly, 
however,  remove  the  brush  to  see  if  the  contact  is  good,  or 
to  see  if  the  commutator  itself  is  black  and  dirty,  or  rough- 
ened, in  which  case,  carefully  clean  it  with  double  O  sand- 
paper. Never  use  emery  paper  on  a  commutator,  since  it 
contains  particles  of  steel  and  iron,  and  you  will  simply 
aggravate  the  trouble  by  smoothing  it  up  with  emery  paper. 
The  principal  thing  with  a  fan  is  to  have  regular  set  times 
for  examining,  oiling  and  cleaning  them,  and  to  exercise  good 
sense  in  caring  for  them.  See  "Care  of  the  Commutator," 
Page  372. 

Another  important  office  of  the  wall  fan  is  the  prevention  of 
pockets  of  foul  air.  This  is  a  matter  which  should  be  carefully 
studied  by  the  architect  who  plans  theatres;  also  by  the 
theatre  manager  himself.  Underneath  the  balcony  and  in 
corners  there  is  always  the  liability  of  pools  of  stagnant  air, 
which  become  heavily  laden  with  impurities,  often  to  such 


628  MOTION    PICTURE   HANDBOOK 

extent  as  to  be  positively  poisonous  and  dangerous.  These 
pockets  easily  may  be  avoided  by  the  judicious  use  of  wall 
or  ceiling  fans. 

Where  the  air  is  forced  in  through  large  openings,  the 
common  and  best  practice  permits  the  location  of  the  in-lets 
to  be  about  six  feet  above  the  floor,  and  the  location  of  the 
out-lets  to  be  in  or  near  the  ceiling.  This  plan,  however, 
has  the  objection  that  if  the  air  which  is  driven  in  is  passed 
over  heating  coils,  or  is  for  any  other  reason  warmer  than 
the  air  inside,  it  immediately  rises  and  passes  out  through 
the  ceiling  ventilators  without  distributing  the  beds  of  foul  air 
next  the  floor  which  the  audience  is  continuously  breathing.  This 
bed  of  air  next  the  floor,  being  cooler  than  the  incoming  air, 
will  remain  at  the  bottom.  On  the  other  hand,  there  is 
serious  objection  to  air  being  driven  in  through  large  floor 
radiators  by  reason  of  the  fact  that  more  or  less  unpleasant 
and  even  dangerous  draughts  are  thus  created.  Where  this 
latter  plan  is  used  the  speed  of  the  air  through  floor  radiators 
should  never  exceed  two  hundred  feet  per  minute. 

It  will  be  seen  from  the  foregoing  that,  as  between  locating 
the  ducts  above  the  floor  level  and  bringing  the  air  in  through 
large  floor  radiators  or  radiators  located  in  the  side  wall  at 
the  floor  line  it  is  a  choice  of  two  evils.  Neither  one  can  by 
any  stretch  of  the  imagination  be  called  ideal. 

The  better  method  and  in  fact  the  only  really  efficient 
method  of  theatre  ventilation  is  the  establishment  of  a  cham- 
ber, preferably  underneath  the  main  floor  of  the  auditorium 
near  the  stage  end,  or  if  there  be  a  stage,  then  preferably 
underneath  the  stage.  The  air  should  be  pumped  into  this 
chamber  by  a  fan  of  proper  design  and  capacity.  The  cham- 
ber itself  should  be  divided  by  two  partitions  of  ordinary 
chicken  wire  stretched  tightly  and  properly  supported.  These 
two  wires  should  be  located  about  three  feet  apart,  and  upon 
the  side  next  the  intake  should  be  stretched  sheets  made  of 
cheesecloth.  The  air  will  thus  be  compelled  to  pass  through 
the  two  thicknesses  of  cloth,  which  intercept  a  large  portion 
of  the  dust.  This  will  not  only  render  it  more  healthful,  but 
will  reduce  the  bills  for  cleaning  and  redecorating.  Back  of 
these  sheets  should  be  the  heating  coils,  steam  heat  being 
the  most  desirable  for  theatres,  in  that  it  is  reasonably  easy 
to  manage,  reasonably  cheap  in  installation,  and  in  the  event 
that  the  plant  should  lie  idle  in  cold  weather  there  is  nothing 
to  freeze  up  but  the  boiler.  The  chamber  containing  the 
coils  should  be  stopped  at  its  inner  end  by  a  shutter  system, 
and  at  one  side  there  should  be  a  by-pass,  also  controlled  by 


FOR   MANAGERS   AND    OPERATORS  629 

shutters,  so  that  by  manipulating  these  shutters  or  dampers 
the  temperature  of  the  air  may  be  regulated.  If  it  is  too 
hot  ease  up  on  the  hot  chamber  damper  and  open  up  a  little 
on  the  Ly-pass,  thus  allowing  colJ  air  to  mix  with  the  warm. 
It  is  also  possible,  though  rather  expensive,  in  summer  time 
to  place  cakes  of  ice  in  this  chamber  and  thus  cool  the  air 
as  it  is  forced  in. 

In  operating  the  air  filter  its  area  must  be  eight  or  ten 
times  the  sectional  area  of  the  in-let  from  the  fan;  also  the 
'cloth  filter  sheets  must  be  removed  at  intervals  for  cleaning 
and  must  be  thoroughly  dried  before  again  being  used.  If 
they  are  not  thoroughly  dried  then  the  dust  blowing  through 
will  form  a  paste  and  stop  up  the  openings  in  the  cloth. 

It  is  only  intended  to  give  ideas  broadly  in  this  article.  It 
is  not  my  purpose  to  go  into  the  matter  deeply,  but  merely 
to  tell  you  or  give  you  an  idea  of  how  the  thing  can  be 
done,  leaving  the  individual  to  work  out  the  details. 

For  small  theatres  of  the  storeroom  variety  such  an 
elaborate  plant  would  not  be  practical.  I  believe  the  venti- 
lation of  such  theatres  may  be  best  accomplished  by  forcing 
air  in  by  means  of  a  suitable  fan,  located  in  an  opening  at 
one  end  of  the  theatre,  preferably  the  curtain  end.  To  be 
effective  the  movement  oi  air  must  be  fairly  rapid.  Remember 
that  in  summer  the  air  pumped  into  the  room  will  be  almost 
if  not  quite  as  warm  as  that  already  inside.  It  must,  therefore, 
depend  for  its  cooling  effect  entirely  upon  the  evaporation  pro- 
duced by  rapid  movement.  Bear  in  mind  the  fact  that  anything 
which  produces  evaporation  lowers  temperature.  You  may  be 
very  warm,  yet,  let  a  fan  blow  air  into  your  face,  and  al- 
though it  is  the  same  ,air,  just  exactly  as  warm  as  it  was 
before,  still  you  feel  decidedly  cooler.  Why?  Because  the 
moving  air  is  producing  rapid  evaporation.  Drop  alcohol  on 
the  back  of  your  hand,  and  although  the  liquid  be  of  even 
temperature  with  the  surrounding  atmosphere,  it  feels  quite 
cold.  This  is  because  it  evaporates  rapidly,  hence  lowers  the 
temperature  of  the  skin  at  the  point  of  contact.  This  being 
true,  it  naturally  follows  if  the  air  be  driven  through  the  room 
fast  enough  to  cause  evaporation  of  perspiration  it  will  not 
only  keep  the  air  within  the  theatre  pure  but  will  also  pro- 
duce a  sensation  of  coolness.  This  cannot  be  carried  to  the 
point  of  producing  a  strong  draught,  since  that  would  be 
highly  dangerous  in  the  production  of  pneumonia  or  at  least 
"bad  colds."  This  plan,  taking  everything  into  consideration, 
is,  I  think,  the  best  for  storeroom  theatres,  though  it  will  re- 
quire fans  of  ample  dimensions  during  hot  summer  weather. 


630  MOTION    PICTURE    HANDBOOK 

The  air  may  be  cooled  by  blowing  it  over  cakes  of  ice,  or 
through  a  maze  of  cold  water  pipes.  This  is  effective,  but 
costly,  unless  there  is  an  unlimited  supply  of  cold  water 
available  at  very  low  cost. 

It  is  also  a  fact  that  three  or  four  large  cakes  of  ice  located 
at  a  convenient  point  in  the  auditorium  will  radiate  a  sur- 
prising amount  of  cool  air  for  quite  a  distance,  and,  moreover, 
the  sight  of  the  ice  has  a  certain  amount  of  auto-suggestive 
effect  on  the  audience. 

Where  a  new  theatre  is  under  construction  it  is  always  ad- 
visable to  consult  a  sanitary  engineer  with  regard  to  the  venti- 
lation of  the  auditorium.  It  is  a  subject  of  too  much  importance 
to  be  in  other  than  thoroughly  competent  hands. 

Ventilating  Toilet  Room. — Toilet  rooms  should  invariably  be 
ventilated  by  suction.  In  other  words,  the  fan  should  pull  the 
air  out  of  the  toilet  room.  Never,  under  any  conditions,  venti- 
late a  toilet  room  by  forcing  air  in.  The  reasons  for  this  I 
think  are  too  obvious  to  require  discussion. 

In  this  connection,  let  it  be  clearly  understood  that  when  it 
comes  to  moving  air,  the  volume  of  movement  will  depend  largely 
upon  the  fan  area.  This  seems  a  simple  statement,  but  when 
you  come  to  think  of  it,  it  really  means  that  every  increase  in 
diameter  is  effective  by  four  times,  £hus:  A  36-inch  exhaust 
fan  will  remove  four  times  the  amount  of  air  that  an  18-inch 
fan  will  move,  both  running  at  the  same  speed.  It  follows  that 
the  larger  fan  is  very  much  better  adapted  to  use  in  theatres 
from  more  viewpoints  than  one.  It  will  move  a  vastly  greater 
amount  of  air  at  a  very  much  lower  speed  than  will  its  smaller 
diametered  brother.  It  will  be  found  as  cheap,  or  cheaper,  in 
first  cost,  to  install  one  large  exhaust  fan  than  two  small  ones 
of  equal  combined  capacity.  It  will  be  found  that  one  large  will 
move  a  cubic  yard  of  air  cheaper  than  will  two  smaller  ones, 
and  that  the  upkeep  cost  of  one  large  fan  will  be  less  than  that 
of  two  small  ones  of  equal  combined  capacity — provided  that  the 
large  and  small  fans  be  of  equal  excellence  in  mechanical  and 
electrical  construction. 

Don't  buy  cheap  fans.  It  costs  more  in  the  first  outlay — 
considerably  more — to  get  good  fans,  but  it  pays  in  the  long  run, 
both  in  money  and  in  the  saving  of  temper.  A  cheap  fan  is  not 
only  ineffective,  but  its  up-keep  is  usually  very  expensive;  also 
its  useful  life  is  short.  Still  worse  than  all  this,  however,  is  the 
fact  that  it  is  a  continual  source  of  annoyance,  because  there  is 
usually  something  wrong  with  it  about  half  the  time,  and  it  is 
generally  out  of  commission  when  most  needed. 

A  great  many  sets  of  rules  are  given  for  figuring  the  necessary 


FOR    MANAGERS   AND    OPERATORS 


631 


capacity  of  fans  to  change  the  air  in  rooms  of  various  dimen- 
sions in  a  given  time. 

I  shall  give  you  one  of  these  rules  which  I  have  selected  as 
the  best,  but  you  must  understand  that  it  is  only  approximate, 
and  cannot  be  wholly  relied  upon,  since  very  much  will  depend 
on  the  kind  and  type  of  fan  used,  as  well  as  its  position,  and 
whether  it  has  free  delivery  or  delivers  through  a  pipe  or 
duct. 

In  figuring  the  necessary  size  of  fan  to  use,  you  must  first 
determine  th  number  of  minutes  in  which  the  air  in  a  given 
room  must  be  changed,  which  is  found  according  to  the  follow- 
ing formula:  The  constant  in  this  instance  is  30  cubic  feet 

Length  X  Width  X  Height 


Seating  capacity  X  Constant 

of  air  per  person  per  minute  for  the  moving  picture  theatre. 
For  instance,  supposing  we  have  a  room  25  feet  wide  by  80  feet 
long,  with  an  18  foot  ceiling,  seating  capacity  200,  the  problem 
would  be  as  follows: 


25X80X18       36,000 


200  X  30 


6,000 


=  6 


We  therefore,  find  that  six  minutes  is  the  time  in  which  it 
would  be  necessary  to  change  the  air  in  such  a  moving  picture 
theatre  room  in  order  to  serve  the  purposes  of  healthful  ven- 


CUBIC  FEET   AIR  IN  ROOM  =  HEIGHT  »  WIDTH  »  LENGTH 


Table  12,  Figure  299. 

tilation.     Diagram,  Table  12,  Fig.  299,  is  taken  from  one  of  the 
advertising  circulars  of  the  Watson  Ventilating  Fan. 


632  MOTION   PICTURE   HANDBOOK 

In  order  to  use  this  diagram  to  find  the  size  fan  necessary 
for  the  foregoing  projblem,  we  will  draw  a  horizontal  line  from 
six  minutes,  which  would  be  a  little  more  than  half  way  be- 
tween five  and  seven  and  a  half.  This  line  will  be  drawn  out 
until  it  crosses  a  -line  opposite  36,000  in  the  cubic  contents 
column,  and  we  find  that  in  order  to  secure  a  change  of  air 
in  six  minutes  we  must  use  a  24-inch  fan,  although  it  will  lack 
a  little  of  the  requirement.  To  make  the  matter  a  little  more 
clear,  first  find  the  number  of  minutes  in  which  the  air  in 
the  room  must  be  changed.  Next  draw  a  horizontal  line  from 
the  time  until  it  crosses  a  line  vertically  from  the  cubic  con- 
tents of  the  room,  and  the  diagonal  fan-size  line  nearest  will 
indicate  the  necessary  size  of  the  fan. 

As  to  Heating,  it  is  too  large  a  subject  to  be  dealt  with  in 
detail  in  this  book.  The  usual  temperature  it  is  desired  to 
maintain  is  70  degrees  Fahrenheit.  There  are  three  available 
methods  of  heating — hot  air,  which  is  comparatively  cheap 
of  installation  but  difficult  to  manage  with  any  degree  of 
satisfaction  when  it  comes  to  heating  a  large  auditorium; 
steam  heat,  which  is  more  costly,  both  in  installation  and 
operation,  than  hot  air;  .and  hot  water,  which  is  the  most 
costly  of  all  to  install,  but  the  cheapest  in  operation.  The 
relative  cost  of  installation  as  between  hot  air,  steam  and 
hot  water  is  9,  13,  and  15;  that  is  to  say,  that  is  the  ratio. 
The  ratio  of  cost  of  operation  is:  Hot  air,  29^4;  steam,  29, 
and  hot  water,  27. 

Steam  seems  to  be  the  system  best  calculated  to  meet  the 
requirements  of  the  theatre.  Its  principal  advantage  is  its 
ability  to  heat  uniformly,  regardless  of  the  action  of  wind 
and  its  comparative  immunity  from  danger  of  freezing.  Steam 
heating  may  be  by  gravity  or  non-gravity  return,  or  may  be 
low  pressure  or  high  pressure. 

Steam  and  hot  water  heat  is  supplied  by  means  either  of 
pipes  or  radiators,  or  both,  and  the  heat  may  be  supplied  by 
locating  the  heating  apparatus  inside  an  air  chamber  and 
blowing  the  air  through  the  coils,  or  by  locating  the  radiators 
inside  the  auditorium,  in  which  case  there  should  be  a  goodly 
amount  of  heating  surface  in  the  foyer,  if  there  is  one,  and 
in  the  entryway,  in  order  to  temper  the  air  drawn  in  through 
the  entrance  and  exit  openings. 

In  order  to  find  the  square  feet  of  direct  radiation  required 
for  a  given  space,  divide  the  cubic  contents  of  the  room  by 
the  following  factors:  Auditorium  in  which  there  are  win- 
dows or  other  exposure,  60;  where  there  are  no  such  open- 
ings, 100.  Dressing  rooms,  one  side  exposed,  divide  by  40  to 


FOR   MANAGERS   AND    OPERATORS  633 

50,  according  to  the  window  space;  dressing  rooms,  with  two 
sides  exposed,  divide  by  30  to  40,  according  to  the  window 
space. 

As  to  the  best  apparatus,  it  would  be  an  almost  endless 
task  to  go  into  that.  For  the  comparatively  small  theatre  I 
think  that  when  we  consider  cost  of  installation  and  efficiency 
the  small  cast  iron  boiler  will  best  serve  the  purpose,  but 
for  a  large  auditorium  the  fire  box  boiler  is,  all  things  con- 
sidered, probably  best.  The  horizontal  tubular  boiler  is  a 
little  more  efficient,  but  it  requires  brick  settings  and  more 
space. 

In  winter  time  it  is  possible  to  secure  very  good  ventila- 
tion of  a  theatre  by  means  of  a  double  smoke  flue  for  the 
boiler  of  the  heating  apparatus.  To  accomplish  this  the  inner 
flue  must  be  of  metal  and  must  be  surrounded  by  a  second 
flue  of  larger  diameter,  the  air  space  between  the  two  being 
connected,  by  a  proper  duct,  to  a  point  near  the  ceiling  of 
the  auditorium.  The  heat  of  the  smoke  flue  will  cause  con- 
siderable suction  in  the  air  space,  and  this,  of  course,  will 
draw  out  the  foul  air  from  the  auditorium. 

Lighting  the  Auditorium 

IT  is  utterly  impossible  to  deal  with  this  subject  except  in 
generalties,  because  conditions  in  different  houses  vary 
so  widely;  also  the  ideas  of  theatre  managers  are  at 
such  variance  on  the  subject  of  auditorium  lighting  that  it  is, 
I  think,  not  advisable  to  attempt  giving  anything  more  than 
such  general  rules  as  will  apply  in  all  cases. 

In  the  first  place,  it  is  absolutely  essential  to  high  class  pro- 
jection, or  even  to  good  projection,  that  no  direct  rays  of  light, 
other  than  those  from  the  lens  of  the  moving  picture  machine, 
be  allowed  to  reach  the  screen.  The  first  important  step  in 
auditorium  lighting  is  to  make  sure  that  there  is  no  light  in  the 
auditorium,  except  the  picture  light  coming  from  the  projector 
lens  and  the  rays  from  the  lighting  system  of  the  auditorium. 

To  test  this  matter,  close  all  the  doors  and  whatever  is 
used  to  darken  the  windows,  switch  off  all  the  auditorium 
lights,  and  see  if  any  light  enters  from  without — this,  of 
course,  applying  to  day  time.  If  any  daylight  enters,  take 
such  steps  as  may  be  necessary  to  exclude  it,  and 

Under  no  circumstances  allow  rays  of  sunlight  to  reach  the 
screen. 

Having  finished  this  test,  next  open  the  entrance  doors 
and  the  doors  through  which  individuals  in  the  audience 


634  MOTION    PICTURE   HANDBOOK 

pass  out  during  the  performance,  and  examine  the  screen 
carefully.  If,  with  these  doors  open,  shadows  appear  on 
the  screen,  then  you  must  take  such  steps  as  will  prevent 
that  condition. 

At  night  the  projection  may  be  injured  by  stray  light 
emanating  from  (a)  operating  room;  (b)  the  piano  or  or- 
chestra lamps;  (c)  incandescent  lights  in  the  auditorium; 
(d)  indirect  lighting  fixtures  wrongly  placed,  or  containing 
too  many  lighted  globes,  or  globes  of  too  high  candle  power. 

Conditions  vary  so  greatly  in  different  houses  that  no  con- 
crete advice  can  be  given,  except  to  advise  the  manager  to 
carefully  examine  into  these  matters,  and  if  stray  light  is 
reaching  the  screen  in  such  way  as  to  cause  its  uneven 
illumination  (the  test  should  be  made  with  the  projector 
light  shut  off)  then  such  steps  should  be  taken  as  will  pre- 
vent that  condition. 

Light  for  the  Musicians. — One  of  the  most  common 
blunders  made  in  moving  picture  theatre  lighting  is  found 
in  the  lights  supplied  to  musicians.  As  a  general  proposition 
they  are  altogether  too  brilliant,  and,  also,  in  many  cases 
are  very  poorly  shaded.  It  is  no  uncommon  thing  to  find 
a  moving  picture  theatre  with  the  piano  close  to  the  screen 
and  its  entire  upper  half  covered  with  white  light  from  a 
16  c.  p.  incandescent  lamp.  This  is  worse  than  foolish.  It 
is  literally  an  outrage,  because  it  adds  an  absolutely  un- 
necessary element  of  eyestrain  which  is  felt  by  practically 
every  one  of  the  audience.  They  look  at  the  picture,  but 
their  eyes  are  either  consciously  or  unconsciously  affected 
by  that  big  splotch  of  white  light  on  the  piano. 

The  piano  light  should  never  be  more  than  6  c.  p.  and  I  be- 
lieve 2  c.  />.  is  ample;  also  it  should  be  so  shaded  that  only  the 
sheet  of  music  being  played  is  illuminated.  This  may  not  be 
quite  so  nice  for  the  musician,  but  it  is  a  whole  lot  better  for 
the  audience. 

Where  there  is  an  orchestra  the  same  thing  applies.  Use 
low  c.  p.  globes  and  pay  very  careful  attention  to  their  shading, 
to  the  end  that  only  the  sheet  of  music  being  played  receives 
illumination.  Light  amber  colored  globes  are  to  be  pre- 
ferred to  white.  There  is  less  glare  and  it  is  easier  on  the 
musician's  eyes. 

Lights  Around  the  Screen. — A  few  years  ago  it  was  a  com- 
mon practice — and  I  am  sorry  to  say  that  practice  is  still 
followed  in  a  few  theatres — to  place  a  row  of  incandescent 
lamps  clear  around  the  two  sides  and  top  of  the  screen,  to 
be  burned  during  intermissions.  This  practice  is  worse  than 


FOR   MANAGERS   AND   OPERATORS  635 

bad.  It  decidedly  is  no  joke  to  be  compelled  to  stare  at  any- 
where from  twenty  to  forty  incandescent  lamps  for  any 
considerable  period  of  time.  Try  it  once  and  see  for  your- 
self. If  your  eyes  don't  hurt  after  the  first  few  minutes  then 
you  certainly  have  a  wonderful  pair  of  optics.  If  you  have 
anything  of  that  sort  in  your  theatre,  Mr.  Manager,  for 
heaven's  sake  yank  it  out,  and  stand  not  upon  the  order  jof 
doing  it.  It  is  a  crime  against  your  audience. 

How  Much  Light. — The  amount  of  light  to  be  used  in  the 
auditorium  is  a  matter  concerning  which  there  has  been  a 
great  deal  of  pretty  hot  debate.  The  self-appointed 
guardians  of  the  morals  of  moving  picture  theatres  (who 
usually  carefully  overlook  the  glaring  defects  in  the  morals 
of  the  burlesque  houses  and  legitimate  stage)  generally  de- 
mand an  utterly  unreasonable  amount  of  illumination  in  the 
auditorium  of  the  moving  picture  theatre,  notwithstanding 
the  fact  that  this  excessive  illumination  serves  absolutely 
no  good  purpose  and  operates  to  very  largely  detract  from 
the  excellence  of  the  show.  It  is  freely  conceded  that  a 
dark  theatre  is  not  an  ideal  condition,  particularly  in  our 
larger  cities,  but 

The  writer  emphatically  insists  that  any  illumination  other 
than  an  amount  sufficient  to  enable  one  standing  in  the  darkest 
portion  of  the  house  to  distinguish  the  features  of  those  around 
him  for  a  distance  of  say  six  of  at  the  most  eight  feet  is  un- 
necessary, and  therefore  undesirable. 

The  only  argument  that  legitimately  can  be  advanced  for 
the  illumination  of  the  auditorium  of  the  moving  picture 
theatre  is  the  possibility  of  improper  conduct  on  the  part 
of  patrons  seated  in  a  dark  auditorium,  but  I  believe  any 
sane  and  unprejudiced  person  will  admit  that  if  there  is 
sufficient  light  to  enable  one  to  distinguish  features  six  to 
eight  feet  away,  there  is  sufficient  light  to  reduce  the  pos- 
sibility of  anything  of  that  sort  to  a  negligible  quantity. 

As  to  the  kind  of  lighting,  the  writer  believes  that  a  prop- 
erly installed  indirect  lighting  system  is,  everything  con- 
sidered, best.  What  is  known  as  the  indirect  lighting  system 
consists  of  incandescent  globes  in  fixtures,  typical  examples 
of  which  are  shown  in  Fig.  300,  the  same  being  entirely 
inclosed  at  the  bottom  and  entirely  open  at  the  top,  so  that 
all  the  rays  of  light  from  the  lamps  within  are  directed  up- 
ward toward  the  ceiling,  whence  they  are  reflected  down- 
ward in  diffused  form. 

There  is  an  almost  endless  variety  of  design  of  these  fix- 
tures, ranging  from  $10  each  to  as  high  as  you  wish  to  go, 


636 


MOTION    PICTURE   HANDBOOK 


FOR    MANAGERS   AND    OPERATORS  637 

some  being  made  of  metal,  some  of  other  opaque  substances, 
and  some  opalescent  or  semi-transparent.  The  last  named  are 
very  pretty,  but  I  very  much  question  the  advisability  of 
using  them.  I  believe  the  opaque  fixture  is  much  better  for 
moving  picture  theatre  lighting.  Properly  selected  indirect 
lighting  fixtures  add  to  the  appearance  of  the  room.  Where 
this  system  is  used  the  ceiling  should  be  of  some  compara- 
tively light  color,  a  cream  or  very  light  tan  or  green  being,  I 
believe  everything  considered,  best. 

Caution:  When  installing  indirect  lighting  systems  great  care 
should  be  had  that  there  are  not  too  many  fixtures  and  that  the 
fixtures  do  not  contain  too  many  lamps  designed  to  burn  during 
the  performance,  or  that  the  lamps  designed  to  burn  during  the 
performance  be  not  of  too  high  c.  p.  It  is  easy  to  overdo  in- 
direct lighting,  and  thus  injure  the  projection.  It  is  well  to 
have  the  installing  company  guarantee  that  the  installation  will 
be  so  made  that  with  the  projection  shut  off  and  burning  the 
indirect  lights  which  will  be  used  while  the  picture  is  on,  the 
illumination  of  the  screen  will  be  uniform  all  over,  without  any 
trace  of  shadow. 

When  installing  indirect  lighting  the  lamps  should,  of 
course,  be  on  two  or  more  circuits,  one  of  which  must  carry 
the  number  of  lamps  it  is  designed  to  use  while  the  picture 
is  on,  and  the  other  circuit,  or  circuits,  to  carry  additional 
lamps  to  be  lighted  during  intermissions,  thus  bringing  the 
auditorium  illumination  up  to  its  full  value  when  the  picture 

is    Off.       BE    CAREFUL   AND   DO    NOT  LOCATE    FIXTURES    TOO    NEAR    THE 
SCREEN. 

Lighting  moving  picture  theatre  auditoriums  is  not  a  matter 
to  be  undertaken  haphazard.  It  is  a  problem  for  an  illumination 
engineer  who  is  thoroughly  versed  in  matters  pertaining  to  the 
projection  of  pictures. 

Shado-Lite. — As  long  ago  as  five  years  the  author  of  this 
work  recommended  the  scheme  of  lighting  illustrated  in 
Fig.  301.  He  still  recommends  that  plan,  and  believes  it  to 
be  ideal,  */  rightly  carried  out.  However,  there  has  been  a 
lighting  scheme  evolved,  known  as  "Shado-Lite,"  illustrated 
in  Fig.  302.  This  plan  seems  to  me  with  a  little  modification 
to  be  excellent.  The  light  is  thrown  on  the  back  of  the 
audience,  and  is  kept  entirely  away  from  the  screen,  the  re- 
flection being  for  the  main  part  downward  and  backward. 
The  only  criticism  I  have  to  make  on  this  scheme  is  that  the 
light  should,  I  think,  not  strike  the  front  theater  wall  at  all, 
but  just  reach  the  top  of  the  front  row  of  seats.  This  plan 
of  lighting  is  put  forward  by  the  Shado-Lite  Manufacturing 


638 


MOTION    PICTURE   HANDBOOK 


Company,  Beaver  Falls,  Pa.    I  would  recommend  it  to  the 
serious  consideration  of  theatre  managers. 


I 


Figure  301. 

In  considering  house  lighting  it  is  well  to  remember  that 
the  decoration  of  the  auditorium  has  very  decided  effect  on 
the  amount  of  light  it  will  be  necessary  to  use.  Illumination 
is  largely  a  question  of  the  .amount  of  light  reflected,  hence 
when  using  an  indirect  lighting  system  a  ceiling  of  light 
color  will  reflect  a  far  greater  percentage  of  light  than  will 
one  of  dark  color.  The  same  is  true  of  the  walls  of  the 
theatre.  The  percentage  of  light  reflected  by  different  sur- 
faces is  given  different  values  by  different  authorities.  I 
think  the  following  is  approximately  correct: 

Per  Cent. 

Black,    without    gloss 1 

Chocolate,  without  gloss 5 

Dark  Red,  without  gloss 13 

Dark  Brown,  without  gloss 14 

Blue,  without  gloss 26 

Yellow,  without  gloss 45 

White,  without  gloss 75 

White,  glossy 85 


FOR    MANAGERS   AND    OPERATORS 


639 


It  must  be  remembered  that  whereas  light  colors  are  more 
cheerful  and  as  a  rule  more  pleasing  to  the  eye,  still  they 
will,  to  a  much  greater  extent  than  will  dark  colors,  reflect 
any  stray  light  there  may  be,  and  thus  cause  maximum  injury 
to  the  projection.  Dark  colors,  on  the  other  hand,  while 
they  give  the  theatre  a  more  sombre  appearance,  serve  an 
excellent  purpose  in  absorbing  or  very  largely  absorbing  stray 
light.  The  best  plan  is  to  steer  a  middle  course  and  select 
colors  neither  very  dark  nor  very  light.  Where  an  indirect 
lighting  system  is  used  in  my  opinion  a  very  light  tan  or 
cream  color  is  best  for  the  ceiling.  It  gives  a  mellow  tone 
to  the  light,  which  is  pleasing  to  the  eye.  For  the  side  walls 


Figure  302. 


there  is  a  wide  range  of  selection,  but  I  would  avoid  bright 
blues,  bright  red,  and  bright  yellows.  In  fact  subdued  tints  are 
always  to  be  preferred  to  extremes  either  in  light  or  dark  colors. 

To  go  into  the  matter  of  colors  fully  and  in  detail  would 
require  a  vast  amount  of  space.  In  fact,  theatre  decoration 
is  a  topic  which  in  itself  would  form  a  very  interesting  book 
of  goodly  size. 

Side  lights  on  the  walls  are  distinctly  objectionable.  They 
serve  no  purpose  which  cannot  better  be  served  by  the  main 
ceiling  lighting  system.  It  is  possible  to  add  greatly  to  the 
decoration  of  the  room  by  carefully  selected  ornamental  opales- 
cent glass  fixtures  containing  a  low  c.  p.  incandescent,  placed 
at  appropriate  intervals  around  the  sides  of  the  room  from 


640  MOTION    PICTURE   HANDBOOK 

six  to  eight  feet  from  the  floor.  One  of  the  most  pleasing 
effects  we  have  yet  seen  used  in  this  connection  is  a  glass 
"torch,"  something  like  two  feet  long,  the  "flame"  lighted 
by  a  small  incandescent.  This  gives  off  no  illumination  at  all, 
merely  serving  as  an  ornament.  The  design  of  these  orna- 
ments are  legion,  and  it  is  up  to  the  manager  to  select  those 
best  suited  to  his  needs,  remembering  always  that  the  colors 
should  be  reasonably  dark.  Don't  try  to  get  any  illumination 
from  the  fixture.  Treat  it  purely  as  an  ornament,  showing 
beautiful  designs,  in  colors,  but  not  too  brightly. 

Shaded  Exit  Lights. — There  is  a  vast  amount  of  crass 
stupidity  or  carelessness  displayed  in  many  theatres  with 
reference  to  the  exit  lights.  Don't  just  have  a  sheet  of  ground 
glass  with  red  or  black  letters  on  it.  So  construct  the  box  for 
the  exit  lights  that  no  light  at  all  can  escape  from  it.  That  is 
very  easy  if  it  is  to  be  electrically  lighted,  but  if  lighted  by  gas 
the  use  of  a  properly  'hooded  ventilator  is  involved.  Paint 
the  space  where  the  letters  will  come  bright  red  and  then 
have  the  letters  blocked  out  in  black  and  all  the  rest  of  the 
glass  painted  black,  so  that  only  the  letters  will  show.  In  case 
you  use  a  stock  ground  glass  with  red  letters  on  it,  my 
advice  is  to  paint  everything  but  the  red  letters  solid  black, 
the  point  'being  that  you  don't  want  any  of  the  white  light 
showing— just  the  red  letters. 

All  too  often  you  find  the  two  front  exit  lights  smearing 
light  all  over  the  front  wall,  their  rays  often  shining  directly 
on  the  screen.  Such  work  is  very  coarse.  It  displays  lank 
stupidity  or  absolute  carelessness  on  the  part  of  the  one  re- 
sponsible, and  either  one  of  those  two  things  spell  incom- 
petency. 

All  auditorium  lights,  except  those  designed  to  be  kept 
burning  during  the  performance,  should  be  handled  by  dim- 
mers, full  description  of  which,  together  with  prices,  etc., 
may  be  had  from  any  dealer  in  general  theatrical  supplies. 
A  gradual  lowering  and  turning  on  of  the  lights  has  ,a  far 
more  pleasing  effect  than  their  switching  off  and  on.  Dim- 
mers are  not  very  expensive  and  are  a  mighty  good  investment. 

SLOPE  OF  AUDITORIUM  FLOOR 

The  question  is  often  asked,  by  those  contemplating  the 
construction  of  a  moving  picture  theatre,  "What  slope  ought 
I  to  give  the  auditorium  floor?"  This  question  is  quite  dif- 
ficult to  answer,  since  it  involves  several  points,  each  of 
which  must  receive  very  careful  consideration. 

In  the  first  place,  the  main  auditorium  floor  and  the  bal- 


FOR    MANAGERS   AND    OPERATORS  641 

cony  floor  present  two  entirely  separate  and  different  prop- 
ositions. The  center  of  the  screen  is  considerable  above 
the  main  auditorium  floor.  Therefore,  since  the  audience 
must  look  upward  toward  the  center  of  the  screen,  it  is  not 
necessary  that  the  main  auditorium  floor  be  given  so  sharp 
a  slope  as  is  necessary  in  the  balcony,  where  the  audience 
must  look  downward  toward  the  center  of  the  screen. 

The  slope  to  be  given  will  necessarily  depend  somewhat 
upon  the  length  of  the  house.  It  will  ordinarily  be  imprac- 
ticable to  give  the  main  auditorium  floor  of  the  long  house 
as  steep  a  pitch  as  is  practical  with  the  short  house.  Where 
the  front  of  the  balcony  is  situated  a  long  distance  from  the 
screen,  it  is  not  necessary  to  have  so  steep  a  pitch  in  the 
balcony  as  where  it  is  up  comparatively  close  to  the  picture. 

As  a  general  proposition  I  believe  that  for  the  main  audi- 
torium floor  one  foot  in  ten  will  be  found  to  be  very  satis- 
factory. Where  it  is  practical  to  do  so  one  may  increase 
this  considerably  with  advantage,  up  to  the  point  where  the 
slope  of  the  aisle  becomes  too  abrupt  for  safety.  Less  than 
one  foot  in  ten  will  not  be  found  entirely  satisfactory.  The 
slope  of  the  balcony  floor  should  be  so  figured  that,  using 
the  center  of  the  screen  for  a  point,  a  line  drawn  to  the  back 
of  a  row  of  chairs  will  come  as  far  above  the  top  of  the 
row  of  chairs  ahead  as  a  line  drawn  from  the  center  of  the 
screen  to  a  row  of  chairs  in  the  auditorium  will  come  from 
the  top  of  the  next  row  ahead,  taking  a  row  of  chairs  in  the 
auditorium  immediately  under  the  balcony  for  an  example. 
This  can  all  very  easily  be  laid  out  on  paper,  and  it  may  be 
found  that  it  will  be  impracticable  to  have  this  amount  of 
slope  to  the  balcony,  but  it  should  be  done  if  possible,  except  in 
cases  where  the  screen  sets  abnormally  high,  or  the  slope 
of  the  main  floor  is  unusually  heavy. 

I  think  you  see  the  idea  I  am  trying  to  convey,  and  will 
understand  that  it  will  of  necessity  have  to  be  modified  to 
fit  circumstances.  One  foot  in  ten  of  slope  will  provide  a 
rise  of  almost  three  inches  between  chair  rows  spaced  28 
inches. 

Above  all  things  avoid  steps,  either  in  the  aisles  or  en- 
tering the  theatre.  Steps  in  an  aisle  are  absolutely  not  to 
be  considered  under  any  circumstances.  In  panic  they  would 
be  highly  dangerous.  Steps  at  the  entrance  cannot  always 
be  avoided,  but  they  are,  nevertheless,  very  bad,  and  wher- 
ever possible  a  slope  should  be  substituted.  Steps  for  the 
seat  rows  very  considerably  increase  the  cost  of  cleaning; 
otherwise  they  are  not  objectionable. 


642  MOTION    PICTURE   HANDBOOK 

Seating 

SEATING  is,  to  the  average  manager,  one  of  the  impor- 
tant problems.  The  first  consideration  in  a  moving  picture 
theatre  is  excellence  in  projection,  and  the  second  is  making 
the  audience  comfortable.  The  requirements  of  moving  pic- 
ture theatre  seating  has,  to  a  considerable  extent,  changed 
during  the  past  two  years.  Just  a  comparatively  short  time 
ago  but  very  few  moving  picture  patrons  expected  to  remain 
longer  than  one  hour.  In  fact  one  hour  was  considered  the 
average  time  for  a  "picture  show."  Now,  however,  some  of 
the  larger,  more  pretentious  city  theatres,  and  in  some  in- 
stances the  better  theatres  in  smaller  cities  are  putting  on 
elaborate  feature  plays,  such  as  "The  Birth  of  a  Nation," 
"Cabida"  and  other  similar  productions,  which  require  two 
hours  or  more  for  their  proper  presentation.  When  the 
patron  only  remains  a  short  time,  a  comparatively  narrow, 
cheap  seat  will  be  quite  satisfactory,  but  when  one  is  to 
remain  in  a  chair  for  two  or  two  and  a  half  hours,  with  only 
one  short  intermission,  or  no  intermission  at  all,  a  very 
different  problem  is  presented.  The  chair  must  then  be 
fairly  commodious,  and  at  least  fairly  comfortable.  Seats 
may  be  18,  19,  20  or  22  inches  wide.  In  small  towns  where  the 
show  is  comparatively  short,  the  seating  space  usually  quite 
limited,  and  the  admission  price  low,  it  is  quite  possible  to 
use  the  19  or  even  the  18  inch  seat  with  fairly  good  results, 
nor  is  it  necessary  to  purchase  expensive  seats.  There 
are  some  very  excellent  theatre  seats  with  wooden  backs  and 
seats,  which  may  be  had  at  surprisingly  low  figures  con- 
sidering the  quality  of  material  and  workmanship.  These 
chairs  ought  to  serve  very  well  in  a  five-cent  house,  or  even 
in  a  small  town  ten-cent  theatre.  In  the  larger  cities,  how- 
ever, where  competition  is  keen,  the  shows  longer,  and  the 
price  of  admission  higher,  the  theatre  manager  will  do  well 
to  use  a  20-inch  seat,  of  at  least  fairly  good  quality.  Imita- 
tion leather  upholstery  may  be  had,  which  is  durable,  hand- 
some, and  very  reasonable  in  price.  I  doubt  the  advisability 
of  using  anything  wider  than  20  inches  in  a  moving  picture 
theatre,  unless  it  be  a  theatre  de  luxe  which  caters  to  a  high 
class  trade  at  good  prices  and  which  presents  a  very  long 
show. 

I  would  in  any  event  strongly  advise  theatre  managers 
religiously  to  avoid  any  kind  of  cloth  upholstery.  It  is  dif- 
ficult to  keep  clean,  is  a  dust  gatherer,  and  adds  materially 
to  the  expense  of  janitor  work;  also  it  is  hot  and  "stuffy." 


FOR    MANAGERS    AND    OPERATORS  643 

Imitation  leather  is  far  superior;  even  plain  wood  is  dis- 
tinctly better. 

I  do  not  propose,  however,  to  dwell  on  this  subject,  since 
regardless  of  what- 1  or  anyone  else  may  say,  it  has  been  my 
observation  and  experience  that  each  manager  is  guided 
largely  by  his  own  ideas  and  the  blandishments  of  seat  sales- 
men in  his  selection  of  seats. 

The  front  row  of  seats  ought  never  to  be  placed  less  than 
20  feet  from  the  screen.  If  the  picture  be  a  large  one,  even 
that  distance  may  well  be  increased.  (See  "Eye  Strain,"  Pages 
153,  175,  472.)  Assuming  the  picture  to  be  12  feet  or  more,  the 
best  view  of  it  is  not  had  until  one  is  at  least  50  feet  from  the 
screen,  and  the  ideal  view  is  had  at  any  distance  between  50  and 
100  feet.  This  item  should  be  taken  into  consideration  by 
managers,  and 

//  there  is  a  difference  in  the  price  of  parquet  seats,  those 
near  the  screen  should  be  the  cheaper.  That  is  the  practice  in 
England,  and  it  is  the  correct  practice.  The  best  seats  are  at 
the  rear. 

Loge  Seats. — One  scheme  successfully  carried  out  in  some 
of  our  western  cities  is  the  placing  at  the  front  of  the  balcony 
and  (or)  at  the  rear  of  the  auditorium  of  a  row  of  boxes 
containing  comfortable  chairs,  preferably  of  wicker  work  of 
neat,  strong  design.  These  loges  or  boxes  will,  if  properly 
arranged,  occupy  the  ideal  picture  viewing  location,  and  the 
seats  therein  should  sell  at  a  considerable  advance  over  par- 
quet seats.  For  instance:  If  parquet  seats  sell  at  25  cents 
loge  seats  should  bring  35  or  40  cents.  You  will  find  that 
when  Willy  Boy  takes  his  inamorata  to  the  show  he  will 
swell  out  his  manly  chest  and  buy  two  loge  seats.  It  costs 
him  20  or  30  cents  extra  and  is  worth  at  least  five  times  the 
amount  to  him  in  gratified  pride,  but  aside  from  the  oppor- 
tunity presented  the  young  gentleman  to  swell  up,  he  really 
gets  his  money's  worth  in  a  more  comfortable  seat,  plus  an 
ideal  view  of  the  picture.  In  a  large  house,  having  a  circular 
balcony  and  a  circular  auditorium  back,  it  is  possible  to  have 
a  great  many  of  these  boxes,  and  they  have  almost  without 
exception  proved  to  be  a  splendid  investment  wherever 
installed. 

Figuring  Seating  Capacity.— Figuring  the  seating  capacity 
of  a  room  of  given  size  is  a  deep,  dense  mystery  to  many,  but 
it  is,  as  a  matter  of  fact,  an  extremely  simple  problem. 

Distance  Between  Rows. — Usually  local  law  specifies  the 
minimum  distance  from  chair  to  chair  back — that  is  to  say, 
the  distance  the  rows  of  chairs  may  be  spaced.  Thirty-tvvq 


644  MOTION    PICTURE   HANDBOOK 

inches  is  a  distance  which  meets  the  requirements  of  comfort, 
and  all  reasonable  requirements  of  safety  as  well. 

It  is  very  poor  policy  to  place  the  chair  rows  too  close  to- 
gether in  an  endeavor  to  increase  seating  capacity.  You  will  lose 
money  by  so  doing.  It  makes  your  patrons  uncomfortable  and 
renders  it  difficult  to  pass  in  and  outt  since  the  knees  of  seated 
patrons  are  jammed  right  up  against  the  row  of  seats  ahead. 
Moreover  in  case  of  panic,  the  rows  being  too  close  together 
create  an  additional  element  of  danger. 

Thirty-two  inches  from  chair  'back  to  chair  back  is  the 
distance  the  writer  advises,  and  he  strongly  advises  against 
anything  less  than  this.  To  secure  additional  comfort  and 
elegance  in  high  priced  theatres  some  even  advocate  a  dis- 
tance of  thirty-six  inches,  but  this  reduces  the  number  of 
seats  very  considerably.  Remember  that  as  chair  backs  al- 
ways slope  backward,  the  higher  the  chair  the  less:  room 
there  will  be  for  patrons  to  pass  in  or  out. 

The  Aisle. — The  width  of  aisles  is  also  usually  covered  by 
local  law.  It  is  difficult  to  give  any  hard  and  fast  rules  to 
this  particular  item,  since  the  size  and  shape  of  the  audi- 
torium cuts  ;a  very  decided  figure  in  the  matter.  Where  the 
banks  of  seats  are  short  from  front  to  rear — that  is  to  say, 
in  a  short  auditorium — it  is  not  necessary  to  have  as  wide  an 
aisle  as  where  the  house  is  very  long.  Particularly  is  this 
true  if  the  banks  of  seats  be  not  very  wide  between  aisles. 
Aisle  width  is  largely  a  question  of  the  comfort  of  the  audi- 
ence in  passing  out  after  the  show  is  over  and  the  providing 
of  ample  space  in  case  of  fire  or  other  panic.  For  the 
ordinary  theatre  auditorium,  Zl/2  feet  at  the  front  is  the 
proper  width  for  center  aisles,  gradually  increasing  in  width 
to  4  feet  at  the  rear.  If  the  aisle  exceeds  40  feet  in  length, 
or  serves  more  than  ten  seats  on  either  side,  then  its  width 
should  be  extended  to  4^  feet  at  the  rear.  Side  aisles  need 
not  have  as  great  a  width  as  the  center  aisle,  by  reason  of 
the  fact  that  they  serve  seats  only  on  one  side,  whereas  the 
center  aisle  serves  seats  on  both  sides. 

Let  us  assume,  for  instance,  that  we  have  a  room  80  feet 
long  by  40  feet  in  width.  The  necessity  for  a  rear  aisle  will 
be  governed  by  local  conditions.  There  may  be  no  necessity 
for  any  at  all.  But  assuming,  for  instance,  that  there  are 
two  entrances,  as  shown  in  Fig.  303,  then  there  ought  to  be  a  6- 
foot  aisle  at  the  rear.  The  front  seats  should  be  20  feet  from  the 
screen,  therefore  we  subtract  20  +  6  =  26  feet  from  seating 
space,  leaving  a  total  of  54  feet  for  seats.  Now  since  the 
aisle  is  more  than  40  feet  long,  we  fix  the  width  of  the  center 


FOR    MANAGERS   AND    OPERATORS 


645 


aisle  at  4  feet,  and  since  the  side  aisle  only  serves  half  as 
many  seats  as  the  center  aisle  we  fix  their  width  at  3  feet 
which,  subtracting  4  +  3  +  3  :=10  feet  from  the  total  width, 
leaves  a  total  of  30  feet.  We  will,  therefore,  have  two  sec- 
tions of  seats,  each  15  feet  wide.  Chairs  may  be  had  in 


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Figure  303. 

varying  widths.  Suppose  we  select  one  20  inches  wide;  15 
feet  equals  180  inches ;  each  row  in  each  section  of  seats  will 
therefore  accommodate  as  many  chairs  as  the  width  of  one 
chair  is  contained  into  the  total  width  of  the  section,  or,  in 
this  case,  as  many  chairs  as  20  is  contained  into  180,  which 
is  nine  times.  We  will  therefore  have  nine  seats  in  each 
row  in  each  section,  or  9  X  2  =  18  in  each  row  in  both  sec- 
tions combined.  If  we  used  18-inch  chairs  we  would  have 
180  -j- 18  =  10  chairs  in  each  row  section,  or  10  X  2  =  20  chairs 
in  each  row  of  seats — a  gain  of  two  chairs  per  row  as  against 
the  20  inch  chair.  If  the  sections  were,  after  deducting  aisle 
space,  only  176  inches  instead  of  180,  then  we  would  lose  one 
chair  in  each  row  of  each  section,  and  have  very  wide  aisles, 
unless  local  law  would  permit  of  contracting  the  side  aisles 
four  inches.  Center  aisles  must  never  be  of  less  width  than 
the  figures  given. 


646  MOTION    PICTURE    HANDBOOK 

The  seating  space  is  54  feet  long  or  deep,  and  54  feet  equals 
648  inches.  Fixing  32  inches  as  the  distance  between  chair 
row,  chair  back  to  chair  back,  we  will  have  as  many  rows  as 
648  -r-  32  =  20,  and  8  inches  over.  We  will  therefore*  have 
twenty  rows  of  seats  with  8  inches  to  spare,  and  since  there 
are  18  seats  in  each  row  we  will  have  a  total  seating  capacity 
of  18  X  20  =  360  seats. 

It  seems  to  me  this  ought  to  be  perfectly  plain,  and  very 
easily  understood.  Local  conditions  will  vary  the  results. 
For  instance:  if  we  could  use  the  additional  6  feet  at  the 
rear,  we  would  have  6  X  12  —72  inches  additional  seating 
space,  which  added  to  the  original  648  inches  would  give  us 
720  inches,  and  720 -f- 32  =22  rows  of  seats  with  16  inches 
over.  We  could  therefore  have  22  rows  of  seats,  and  by  de- 
creasing the  distance  from  the  screen  by  \l/2  feet  could  have 
23  rows. 

It  would  be  utterly  impossible  to  take  up  and  consider  all 
the  various  hundreds  of  conditions  which  may  arise,  but  the 
principle  is  always  the  same,  and  is  easy  of  application.  Here 
is  the  rule: 

Subtract  from  the  total  length  of  the  house  the  distance  from 
the  screen  to  the  front  row  of  chairs,  and  the  width  of  any 
aisle  there  may  be  at  the  rear  of  the  last  row  of  seats.  This 
gives  you  the  total  length  of  your  seating  space,  which,  re- 
duced to  inches  and  divided  by  the  inches  from  chair  back  to 
chair  back  (I  recommend  32  inches},  gives  the  total  number  of 
rows  of  seats. 

Lay  out  the  width  of  the  house  on  paper,  to  scale,  leaving 
space  equal  to  the  width  of  the  aisles,  and  thus  determine  the 
exact  width  of  each  section  of  seats.  Reduce  the  width  of  each 
section  to  inches,  and  divide  by  the  width  of  the  chairs  you 
have  selected,  in  inches.  This  will  give  you  the  number  of 
chairs  in  each  row  of  each  section  of  seats,  which  multiplied 
by  the  number  of  rows  in  the  section  will  give  you  the  total 
number  of  chairs  it  contains.  Proceed  thus  with  each  section, 
and  then  add  the  total  together  and  you  will  have  your  total 
seating  capacity. 

Where  the  auditorium  is  built  especially  for  a  theatre  and 
has  curved  rows  of  seats,  it  is  presumed  that  the  architect 
will  plot  out  the  floor,  and  tell  you  the  seating  capacity. 
However,  if  you  are  your  own  architect  you  will  simply  be 
obliged  to  lay  the  whole  thing  out  to  scale  and  plot  it,  since 
if  the  sections  or  banks  of  seats  be  fan-shaped,  there  will  be 
a  greater  number  of  seats  in  each  section  at  the  rear  than  at 
the  front.  Here  again  you  simply  have  to  figure  the  length 


FOR    MANAGERS   AND    OPERATORS  647 

in  inches  of  each  space  and  divide  by  width  of  chairs  se- 
lected to  determine  number  of  seats.  In  fan-shaped  banks  of 
seats  it  might  even  be  permissible  slightly  to  contract  the 
width  of  aisle  toward  the  screen  in  order  to  place  a  given 
number  of  seats  in  the  shorter  spaces,  but  on  no  account 
should  the  aisles  be  narrowed  toward  the  rear  or  exits,  even 
if  local  regulations  permit. 

CARPETING 

Theatre  aisles  should  be  carpeted  with  some  deadening 
material,  such  as  heavy  linoleum,  cork  matting  or  fibre  mat- 
ting. The  latter,  however,  is  not  to  be  recommended  for 
the  same  reason  which  bars  the  use  of  carpet;  it  collects 
too  much  dirt,  and  on  rainy  days  becomes  literally  a  dirt 
reservoir. 

Some  managers  who  have  cement  floors  prefer  not  to  use 
any  covering  at  all,  but  this,  I  think,  is  not  good  practice. 
It  looks  too  bare  and  cold.  I  believe  that  linoleum,  care- 
fully selected  as  to  pattern,  or  cork  matting  are  always  well 
worth  the  cost  as  a  covering  for  theatre  aisles.  This,  of 
course,  does  not  apply  to  the  gallery,  if  there  is  one,  but  it 
does  apply  to  the  balcony.  Where  a  theatre  has  a  main  floor, 
balcony  and  gallery,  the  latter  is  usually  largely  turned  over 
to  the  use  of  more  or  less  rough  boys,  who  care  little  or 
nothing  for  the  finer  refinements  of  life,  and  a  bare  floor 
will  probably  suit  them  just  as  well  as  anything  else,  but 
down  below  these  things  not  only  add  to  the  appearance, 
but  they  prevent  annoyance  to  the  audience  by  the  noise  of 
people  coming  in  and  going  out. 

Cork  matting  of  good  grade  is  expensive,  but  it  forms  an 
ideal  floor  covering,  in  that  it  is  not  only  an  excellent  noise 
deadener,  but  also  is  not  slippery  when  wet;  also  it  is 
handsome  in  appearance  and  is  clean  and  sanitary.  It  may 
be  attached  firmly  to  the  floor  and  remain  there  until  it  is 
worn  out,  an  important  point  in  its  favor.  There  are  two 
minor  objections  to  linoleum,  the  first  being  that  it  is  a 
little  more  slippery  than  cork  matting,  which  is  objection- 
able on  wet  days,  if  the  aisles  are"  steep;  also  in  damp 
weather  it  has  a  certain  tendency  to  expand  and  wrinkle  up. 
Cocoa  matting,  firmly  secured  to  the  floor,  is  the  best  thing 
to  prevent  slipping  on  steep  aisles,  but  it  is  also  the  finest 
dirt  reservoir  imaginable.  Where  it  is  used  it  should  be 
taken  up,  carried  out  doors  and  beaten,  and  the  floor  under 
it  cleaned  every  day. 


648 


MOTION    PICTURE   HANDBOOK 


BELL  WIRING 

I  do  not  think  I  could  improve  matters  by  changing  the 
text  matter  on  this  subject  as  contained  in  the  second  edi- 
tion, therefore  it  is  .reproduced  just  as  it  was. 

The  electric  bell  and  annunciator  play  quite  an  important 
part  in  the  scheme  of  things  in  a  theatre.  The  installation 
of  a  single  bell  is  a  very  simple  matter — so  simple,  indeed, 
that  a  child  might  successfully  install  one.  It  is  illustrated 
in  Fig.  304.  After  installing  the  bell  and  the  push-button  in 
the  location  desired,  one  wire  is  run  directly  from  one  side 
of  the  push-button  to  the  bell.  Another  wire  is  run  from  the 
other  side  of  the  bell  to  one  side  (either  one,  it  makes  no 
difference)  of  the  battery,  and  another  wire  is  run  from  the 
other  side  of  the  battery  to  the  other  side  of  the  push-button. 
This  completes  the  installation.  For  a  single  bell  one  battery 
alone  or  two  batteries  in  series  may  be  used.  By  series  I 
mean  two  batteries,  with  the  carbon  of  one  battery  connected 
to  the  zinc  of  the  other  battery  by  means  of  a  short  wire, 
as  at  A,  Fig.  306.  The  effect  of  two  batteries  connected  thus 
is  to  cause  the  bell  to  ring  louder.  Two  batteries  in  series 
will  not  last  twice  as  long  as  will  one  working  alone. 


O 


Figure  304. 

The  ordinary  practice  in  moving  picture  theatres  is  to  use 
either  bells,  buzzers,  or  small,  low  candle  power  lamps  for 
signaling  to  the  operating  room,  piano  player  and  the  man- 
ager. Of  the  three,  the  lamp  system,  if  properly  installed,  is 
the  best,  with  the  buzzer  as  second.  The  bell  should  never 
be  used.  A  buzzer  is  merely  an  electric  bell  without  the  bell 
part. 

What  is  known  commercially  as  the  dry  battery  is  best  for 
theatre  work.  Wet  batteries  are  very  effective,  and  very 
cheap  in  operation,  but  they  are  liable  to  freeze  up  in  winter 


FOR    MANAGERS   AND    OPERATORS 


649 


and  thus  cause  a  lot  of  trouble.  The  dry  battery  is  cheap 
and  effective. 

It  is  possible  to  renew  dry  batteries  when  they  have  "run- 
down" by  taking  off  the  cardboard  casing  and  punching  sev- 
eral holes  in  the  lead  casing  about  an  inch  from  the  top;  being 
careful,  however,  not  to  break  the  carbon  of  the  battery  in 
the  process.  An  ordinary  nail  may  be  used  to  punch  the 
holes.  Be  careful  also  not  to  disturb  the  sealing  wax  around 
the  top.  Having  done  this,  immerse  the  batteries  in  a  solution 
of  one  pound  of  sal  ammoniac  to  one  gallon  of  water,  and 
leave  them  for  an  hour  or  so,  after  which  remove  and  stand 
them  upside  down  for  one  <hour,  to  allow  the  surplus  solution 
to  thoroughly  drain  out.  In  draining  the  batteries  be  careful 
that  the  solution  does  not  form  a  contact  between  two  bind- 
ing posts,  since  it  will  carry  current,  and  will  thus  short-cir- 
cuit the  battery  and  run  it  down  rapidly.  When  thoroughly 
drained,  wipe  the  battery  dry,  replace  the  cardboard  casing 
and  it  is  ready  for  use. 

For  wiring  bells  No.  18  ordinary  cotton  covered  bell  wire  is 
plenty  good  enough,  unless  the  circuit  be  a  very  long  one,  in 
which  case  No.  16  might  be  used.  This  holds  good,  except  in 
very  wet  places,  where  it  is  better  to  use  rubber  covered 
wires,  supported  upon  porcelain  insulators. 

In  putting  up  bell  wires  they  may  be  gathered  together  in  a 
cable  and  held  to  the  wall  with  a  wooden  cleat.  They  may 
be  run  singly  around  picture  molding,  being  held  thereto  by 


Figure  305. 

small  iron  staples,  but  where  this  is  done  a  staple  should 
never  be  driven  over  two  wires,  since  it  is  likely  to  cut 
through  the  insulation  and  short-circuit  the  bell,  the  battery 
or  both.  Never  drive  a  staple  over  two  wires.  Hold  each 
wire  with  its  own  staples.  A  short  circuit  may  cause  your 


650  MOTION    PICTURE    HANDBOOK 

bell  to  ring  all  the  time  or  not  ring  at  all,  according  to  its 
location.  If  on  the  two  wires  leading  to  the  push-button  the 
bell  will  ring  continuously  until  the  battery  is  worn  out.  Tf 
on  the  wire  running  from  bell  to  battery  and  the  wire  run- 
ning from  button  to  bell  the  bell  will  not  ring  at  all.  Joints 
in  the  wire  should  be  made  in  the  usual  way  (see  wire 
splices,  Page  89),  and  should  be  soldered  and  wrapped  with 
insulating  tape.  Never  run  your  wires  in  a  slipshod  manner. 
Always  do  a  job  in  a  workmanlike  way.  Stretch  the  wires 
tightly  and  run  them  as  they  should  be  run.  Loose,  sagging 
wires  advertise  the  poor  workman. 

A,  Fig.  306,  shows  series  connection  of  batteries,  which 
has  the  effect  of  raising  the  pressure  approximately  one  volt 
for  each  battery  added.  B  shows  multiple  connection,  which 
increases  amperage  but:  not  the  voltage,  and  C  a  series- 
multiple  connection  which  increases  both  volts  and  amperes. 

A  very  common  practice  in  theatres  is  to  use  what  is 
known  as  the  three  wire  system  of  bell  wiring.  This  system 
is  the  most  economical  in  that  it  requires  a  comparatively 
small  amount  of  wire  for  the  installation  of  several  bells.  By 
its  use  any  number  of  bells  may  be  rung  with  one  battery, 
and  each  bell  has  its  own  individual  push-button.  No  push- 
button will  ring  any  bell  but  its  x>wn.  Put  up  the  bells,  buzz- 
ers, or  lights  and  the  push-button  wherever  you  wish  them  to 
be.  Use  two  batteries,  connecting  the  carbon  of  one  to  the 
zinc  of  the  other.  Get  bell  wire  of  three  different  colors.  The 
installation  is  illustrated  in  Fig.  305,  in  which  A-A-A  are  bells, 
B-B-B  push-buttons,  and  .C  a  two-cell  dry  battery. 

The  reason  for  three  colors  is  to  avoid  mistakes  and  confusion 
and  to  be  able  to  find  any  particular  wire  anywhere  afterward, 
without  tracing  it  clear  from  the  battery  or  bell.  The  use  of  three 
colors  of  wire  simplifies  matters  very  greatly.  Suppose  you  get 
red,  blue  and  white.  You  take  one  color,  say  the  blue,  and  run  it 
from  one  (either)  binding  post  of  the  battery  to  one  (either) 
binding  post  of  each  bell.  You  may  run  separate  wires  from  the 
battery  binding  post  to  each  bell  or  run  one  wire  reaching  all  bells 
or  you  may  branch  off  to  a  bell  at  any  point.  Next  take  another 
color  (red,  for  instance),  and  run  from  the  other  battery  binding 
post  to  one  (either)  side  of  each  push  button.  You  now  have  one 
side  of  the  battery  connected  to  one  side  of  each  bell  and  the 
other  side  of  the  battery  connected  to  one  side  of  each  push- 
button. You  next,  with  the  remaining  color  (white)  wire,  con- 
nect the  remaining  side  of  each  push-button  with  the  remaining 
side  of  the  bell  it  is  to  ring,  and  the  job  is  done.  The  blue  wire 
(blue  in  this  case)  is  called  the  common  bell  wire,  the  red  wire 


FOR    MANAGERS    AND    OPERATORS 


651 


is  called  the  push  button  wire  and  the  whites  are  called  the  in- 
dividual wires.  It  is  these  latter  wires  which  determine  which 
bell  a  button  will  ring  and  you  may  cause  a  button  to  ring  a 
different  bell  by  simply  changing  the  individual  wire  to  that  bell. 
Fig.  305  shows  a  plan  of  this  system. 


Figure  306. 

An  additional  bell  easily  may  be  installed  at  any  time  as  fol- 
lows :  Test  the  bell  and  install  it  and  its  push-button  wherever 
you  want  them  to  be.  Now  with  a  piece  of  first  color  wire  con- 
nect one  binding  post  of  the  bell  with  the  first  color  wire  already 
in  use  wherever  you  can  find  it.  With  a  piece  of  second  color  wire 
connect  one  side  of  the  push-button  with  a  second  color  wire 
wherever  you  can  find  one.  Understand  you  can  just  tap  on  to 
these  wires  at  any  point  you  can  locate  one  of  proper  color.  Now 
connect  the  remaining  side  of  the  button  with  the  remaining  side 
of  the  bell  with  third  color  wire  and  the  job  is  done.  The  rules 
governing  this  system  of  wiring  are  as  follows :  One  side  of  the 
battery  must  be  connected  with  one  side  of  each  bell  by  first 
color  wire.  The  other  side  of  the  battery  must  be  connected 
to  one  side  of  each  push-button  with  second  color  wire  and  the 
remaining  side  of  each  button  must  be  connected  with  the  remain- 
ing side  of  the  bell  it  is  to  ring  with  third  color  wire. 

The  various  battery  combinations  are  illustrated  in  Fig.  306. 
A  increases  the  voltage  without  affecting  the  amperage.  B  in- 
creases amperage  without  affecting  voltage.  C  increases  amperage 
and  voltage.  A  is  series,  B  multiple  and  C  is  a  multiple  of  series. 


652  MOTION   PICTURE   HANDBOOK 

In  Fig.  307  we  see  two  fire  bells,  one  located,  let  us  suppose,  in 
the  manager's  office,  and  the  other  on  the  stage,  or  at  any  other 
suitable  point.  We  also  see  an  ordinary  push-button  at  A,  and 
a  form  of  contact  more  suitable  to  such  work  at  B,  either  of 
which  will  ring  both  bells.  As  many  of  these  may  be  attached 
as  desired,  locating  them  at  any  point  in  the  house.  Attach  one 


ffi 

r 


Figure  307. 

side  of  the  button  to  upper  wire  and  the  other  side  to  the  bat- 
tery wire,  as  shown.  In  the  illustration  we  see  four  batteries  con- 
nected in  series.  This  being  a  fire  alarm  system,  it  is  desired 
that  the  bell  or  buzzers  ring  very  loudly,  hence  several  batteries 
are  connected  in  series.  Employees  should  be  made  to  under- 
stand that  it  will  mean  instant  dismissal  to  ring  these  bells,  ex- 
cept in  case  of  actual  necessity.  The  system  can  be  arranged 
for  any  number  of  bells,  from  one  to  a  dozen,  and  there  can  be 
as  many  push-buttons  as  desired. 


Figure  308. 

Fig.  308  illustrates  the  method  of  connecting  a  bell  so  that  it 
may  be  rung  by  more  than  one  button.  By  this  plan  as  many  but- 
tons may  be  installed  as  desired,  any  one  of  which  will  ring  the 
bell,  provided  the  wire  from  push-button  to  battery  wire  be  not 
connected  between  battery  and  bell.  A-A-A  are  push-buttons. 

In  Fig.  309  we  see  the  method  of  wiring  an  ordinary  an- 
nunciator. The  plan  is  too  plainly  shown  to  require  explanation. 
The  buttons  may,  of  course,  be  located  anywhere  in  the  build- 
ing, and  are  ordinarily  widely  separated. 


FOR    MANAGERS   AND    OPERATORS 


653 


Electric  Programme  Board.  Fig.  310  is  the  wiring  diagram 
of  an  electric  programme  board.  I  think  the  action  will  be 
plain  when  you  trace  through  the  contacts  in  Fig.  310. 


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Figure  309. 

Wire  A,  we  may  call  the  permanent  connection.  As  you  will 
observe,  it  connects  directly  to  one  side  of  all  the  lamps.  Wire  B 
connects  through  switch  C  and  movable  arm  D  to  the  various 
contacts  1,  2,  3,  4,  etc.  Now  suppose  we  place  arm  D  on  contact 
1.  You  will  observe  that  the  current  will  flow  through  wire  E. 
through  lamp  1,  and  thence  back  through  the  other  wire,  and 
that  no  other  lamp  will  be  affected.  If  we  move  the  arm  to  con- 
tact 6,  then  only  lamp  6  will  be  lighted.  Such  a  board  is  simple, 


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123 


145  6 


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.EXTRA 


Figure  310. 


entirely  practical,  and  as  I  have  said,  is  the  best  plan  I  have  seen. 
It  is  also  quite  possible  to  substitute  single  pole,  single  throw 
knife  switches  for  contacts  1,  2,  3,  4,  etc.,  connecting  wire  B  to 


654 


MOTION    PICTURE    HANDBOOK 


one  side  of  all  these  switches.  The  switches  or  the  contacts  should 
be  located  at  the  most  convenient  point,  either  on  the  stage,  by 
the  side  of  the  musician  or  in  the  operating  room.  The  trans- 
parency can  be  so  made  that  only  the  figure  or  name  actually 
illuminated  will  be  visible.  This  may  be  done  by  covering  the 
whole  front  of  the  board  with  ground  glass,  on  which  are  the 
figures,  or  names  blocked  out  in  black,  as  shown  in  the  illustra- 
tion, each  lampi  however,  being  contained  in  a  light  tight  com- 
partment of  its  own.  Different  colors  may  be  obtained,  if  de- 
sired, by  covering  the  various  characters  with  light  shades  of 
gelatine  or  using  colored  globes. 

In  practice,  I  would  by  all  means  advise  a  double-pole  single- 
throw  switch  at  AB,  rather  than  the  single-pole  knife  switch  at  C. 
In  fact  switch  C  would  be  a  violation  of  Underwriters'  rules. 


Figure  311. 

In  Fig.  311  a  battery  of  36  lamps  is  arranged  in  the  form  of  a 
square,  with  6  lamps  either  way.  One  wire  (wire  A,  in  the 
sketch)  is  connected  directly  to  one  side  of  each  lamp.  A  board 
is  now  made,  containing  36  sockets,  arranged  in  a  square,  with  6 
s.ockets  each  way,  the  same  as  are  the  lamps.  This  board  may  be 
placed  in  any  convenient  location,  either  near  the  lamps  or  re- 
moved at  a  distance  from  them,  as  may  be  most  convenient;  but 
in  any  event,  the  other  side  of  each  one  of  the  lamp  sockets  must 
be  connected  to  one  side  of  each  socket  as  shown.  We  now  con- 
nect the  other  side  of  each  one  of  these  sockets  to  wire  B,  as 
shown  in  the  illustration,  installing  a  double  pole,  single  throw 
switch,  at  any  convenient  point  in  wires  A,  B.  Both  sides  of  the 
socket  are  now  alive,  one  directly  from  wire  B  and  the  other 
by  way  of  the  lamps  through  wire  A.  It  will  be  readily  seen 
that  if  an  ordinary  plug  fuse  be  screwed  into  any  one  socket  the 
lamp  connected  to  that  socket  by  cross  wire  will  immediately 


FOR    MANAGERS   AND    OPERATORS  655 

be  lighted  and  will  burn  until  the  plug  is  removed.  Suppose 
we  wish  to  form  a  figure  3.  It  would  be  only  necessary  to  in- 
sert the  plugs  in  the  sockets  indicated,  in  order  to  outline  the 
figure  3  on  the  board,  wherever  it  might  be  placed.  In  using 
such  a  plug  board  it  is  advisable  to  have  a  pattern  of  the  various 
figures  and  letters  it  is  desired  to  use.  Patterns  may  be  made 
of  cardboard. 

Where  printed  programmes  are  used  it  is  quite  possible  to  in- 
stall such  a  board  at  the  side  of  the  stage,  with  the  plug  board 
and  the  switch  controlling  the  supply  wires  located  in  the 
operating  room,  within  convenient  reach  of  the  operator.  He  can 
then  plug  in  any  desired  number  and  illuminate  the  same  by 
merely  throwing  in  the  switch,  i.  e. :  Supposing  he  is  running 
reel  2,  the  next  being,  of  course,  reel  3,  which  is  described  on 
the  programme  under  that  number.  He  prepares  Fig.  3  by  placing 
the  plugs  in  position  in  the  board,  and  as  reel  2  is  finished  he 
throws  in  the  switch,  illuminating  Fig.  3,  thus  allowing  the  audi- 
ence to  look  at  the  programme  while  the  next  reel  is  being 
threaded  or  during  the  interval  between  the  two  reels.  Where 
only  one  number  is  to  be  used  the  board  can  be  made  very  small, 
and  it  is  riot  necessary  to  use  more  than  two  or  three  c.  p.  lamps, 
these  being  of  the  proper  voltage  of  course.  Such  a  board  can  be 
used  to  decided  advantage  in  many  ways.  The  lamps,  if  used 
within  the  auditorium,  should  be  frosted  or  else  heavily  colored. 
It  is  possible  to  so  connect  the  various  figures  through  batteries 
of  switches  that  the  plug  arrangement  is  unnecessary.  This  is 
more  costly,  and  the  plug  serves  every  purpose.  It  is  quite  pos- 
sible to  substitute  single  pole,  single  throw  switches,  or  ordinary 
snap  switches  in  place  of  the  plugs.  The  arrangement  shown 
in  Fig.  311  is  much  the  best  for  programme  announcements. 

Electric  Meters 

WHAT  is  known  as  the  watt-hour  meter  is  the  instru- 
ment now  used  for  the  measuring  of  electric  current. 
The  measurement  is  in  watt-hours,  which  simply 
means  that  a  certain  number  of  watts  have  been  used  for  a 
certain  number  of  hours,  one  watt  used  for  one  hour  being 
the  unit  of  measurement.  The  principle  of  operation  of 
these  meters  is  as  follows:  The  dials  which  record  the  con- 
sumption are  operated  by  a  small  motor  which  is  placed  in 
series  with  the  current  consuming  apparatus.  The  motor  is 
so  constructed  that  if  it  were  operated  at  a  pressure  of  one 
volt  for  a  period  of  one  hour  during  which  time  one  ampere 
of  current  flowed,  it  would  record  one  watt,  or  one  "watt- 


656  MOTION   PICTURE   HANDBOOK 

hour."  In  other  words,  if  the  recording  motor  be  run  by  one 
ampere  at  one  volt  for  a  period  of  one  hour  it  would  move 
the  dial  only  just  far  enough  during'  that  hour  to  record  one 
watt-hour.  Using  this  as  a  basis  we  can  readily  understand 
that  if  the  pressure  be  100  volts  and  the  number  of  amperes 
be  2,  during  the  period  of  one  hour  the  meter  would  record 
100  X  2  =  200  watt-hours,  or  if  the  voltage  be  110  and  the 
number  of  amperes  flowing  20,  then  during  a  period  of  one 
hour,  the  meter  would  record  110X20  =  2200  watt  hours, 
which  would  mean,  in  effect,  that  2,200  watts  had  been  used 
for  a  period  of  one  hour,  since  it  would,  under  these  condi- 
tions, require  one  hour  for  the  recording  hand  to  reach  the 
2,200  watt-hour  mark.  Briefly,  the  foregoing  describes  the 
principle  of  operation.  I  hardly  think  it  is  either  necessary 
or  advisable  to  consume  space  in  setting  forth  a  diagram- 
matic representation  and  elaborate  explanation  of  the  meth- 
ods by  which  this  action  is  accomplished. 

Rough  Test  of  Meter. — The  construction  of  electric  meters 
has  reached  such  a  stage  of  perfection  that  it  is  very  seldom 
indeed  that  they  do  not  record  the  current  consumption  with 
perfect  accuracy.  However,  he  who  has  doubt  as  to  the 
correctness  of  his  meter  may  make  a  rough  test  by  putting 
in,  say,  ten  new  incandescent  lamps,  the  wattage  consumption  of 
which  is  at  least  approximately  known,  and  carefully  shut- 
ting off  all  other  current  consuming  devices  and  disconnecting 
the  operating  room  leads,  allowing  these  lamps  to  burn  for 
precisely  one  hour,  first  having  marked  the  exact  position  of 
the  meter  dial  hands.  At  the  end  of  the  hour  shut  off  the 
lamps  and  take  another  reading. 

Caution. — In  doing  this  you  should  turn  the  lamps  all  on 
and  off  at  once,  and  not  with  the  socket  snap  switches,  since 
the  time  consumed  in  turning  off  ten  separate  lamps  by  their 
socket  buttons  would  make  an  appreciable  difference.  Sup- 
pose you  have  ten  SS-watt  lamps,  then  the  meter  would  show 
a  consumption  of  550  watts,  or  550  watt-hours  during  the  one 
hour  test,  but  of  course  the  test  is  only  a  rough  one,  since 
lamps  seldom  consume  exactly  their  rated  wattage.  The 
reason  for  disconnecting  the  operating  room  leads  is  to  avoid 
possibility  of  a  ground  in  the  operating  room  affecting  results. 

It  is  well,  occasionally,  the  last  thing  at  night,  after  every- 
thing has  been  turned  off,  with  a  match  for  illuminant,  to 
take  a  careful  reading  of  the  meter,  and  then  in  the  morning 
before  anything  is  turned  on  take  another  reading.  If  there 
is  any  difference  look  for  a  ground  somewhere  in  your  lines. 
This  may  be  made  more  effective  by  leaving  the  operating 


FOR   MANAGERS   AND    OPERATORS  657 

room  arc  lamp  circuit  switches  in,  but  with  the  carbons 
separated. 

The  unit  of  quantity  in  which  electrical  power  is  meas- 
ured, and  on  which  your  power  bills  are  based,  is  the  watt- 
hour,  or  the  amperes  times  volts  times  hours.  One  watt- 
hour  is  the  equivalent  of  one  ampere  multiplied  by  one  volt 
multiplied  by  one  hour.  A  55-watt  incandescent  lamp  will 
consume  55  watt-hours  in  one  hour — that  is  to  say  it  will 
consume  that  amount  of  power  if  it  is  actually  using  what 
it  is  supposed  to  use,  a  thing  which  seldom  is  true.  There- 
fore if  you  use  twenty-five  55-watt  lamps  for  four  hours, 
your  light  bill  will  be  55  X  25  X  4  =  5,500  watt-hours,  or,  5^ 
kilowatt-hours  ("kilowatt-hours"  being  a  term  which 
means  1,000  watt-hours).  If  your  rate  be  8  cents  per  kilowatt- 
hour,  then  the  bill  for  that  power  would  be  5.5  X  8  =  44  cents. 

There  are  several  different  types  of  meters,  but  the  principle 
of  operation  is  the  same  in  all.  For  alternating  current  the 
apparatus  must,  of  course,  be  adapted  for  use  with  that  kind 
of  power,  but  I  think,  with  those  details  the  operator  is  not 
particularly  interested. 

Reading  the  Meter. — An  electric  meter  is  read  precisely  as 
you  would  read  a  gas  meter.  First  carefully  note  the  unit 
in  which  the  dials  are  read.  On  all  meters  used  by  the 
Edison  Company  the  figures  above  or  below  the  dial  indicate 
the  value  of  one  complete  revolution  of  the  pointer,  hence 
one  division  indicates  one-tenth  of  the  value  of  the  complete 
revolution.  Carefully  note  the  direction  of  rotation  of  the 
dial  pointers,  as  indicated  by  the  figures,  the  pointers  mov- 
ing of  course,  to  figure  1,  to  figure  2,  and  so  on  around 
through  figure  9  back  to  0;  also  each  dial  will  read  in  an 
opposite  direction  to  its  neighbor.  Counting  from  the  right 
on  the  five-dial  register  the  pointers  of  the  first,  third  and 
fifth  dials  of  a  watt-hour  meter  rotate  in  the  direction  of  the 
lhands  of  a  watch,  or  to  the  right,  while  the  hands  of  the 
second  and  fourth  dials  move  in  the  opposite  direction.  The 
same  is  true  of  the  four-dial  register — the  first  and  third 
dials  move  to  the  right  and  the  second  and  fourth  to  the 
left.  The  dials  must  always  be  read  from  right  to  left  and 
the  figures  set  down  as  read,  carefully  remembering  that 
until  the  hand  has  reached  a  division  that  division  does  not 
count.  For  instance:  In  No.  3,  Fig.  312,  the  right  hand  dial 
has  passed  1,  but  has  not  reached  2,  therefore  it  reads  1,  like- 
wise the  second,  or  100  dial  hand  has  passed  2  but  has  not 
reached  3;  therefore  it  reads  2. 

Taking  No.   1,  Fig.  312,   for  example,   it   reads   as    follows: 


658 


MOTION    PICTURE    HANDBOOK 


A  complete  revolution  of  the  right-hand  dial  would  be  1,000 
watt-hours,  but  the  pointer  has  just  reached  division  1,  which 
being  one-tenth  of  1,000,  is  100.  We  therefore  put  down  100. 


10.000.000 


WATT  HOURS 


No.   1. 


No.  3. 


10.000.000 


WATT  HOURS 


10.000 


1.000 


KILOWATT  HOURS 


No.  2. 


No.  4. 


Facsimiles  of  Meter  Dials. 
Figure  312. 

The  next  dial  stands  at  1,  which  since  one  division  is  one- 
tenth  of  the  total  of  10,000  equals  1,000,  therefore  we  set  down 
1  at  the  left  of  the  100,  and  have  1,100.  The  next  dial  also 
stands  at  1,  which  being  one-tenth  of  100,000  is  10,000,  so  we 
set  down  another  1  to  the  left  of  the  1,100  and  we  have  11,100. 
The  next  dial  stands  at  1,  so  we  set  down  another  1  to  the 
left  and  have  111,100,  and  last,  the  1,000,000  dial  stands  at  1, 
which  call  for  still  another  1  at  the  left  and  we  have  a  final 
reading  of  1,111,100  watt-hours. 

Taking  No.  3,  which  reads  in  kilowatt-hours,  we  apply  the 
same  principles.  The  right  hand  dial  registers  up  to  10  kilo- 
watt-hours. The  pointer  has  passed  the  1,  but  has  not 
reached  the  2,  so  we  put  down  a  1,  that  being  one-tenth  of 
the  total  of  10.  The  next  dial  to  the  left  has  passed  the  2 
but  has  not  reached  the  3,  therefore  we  put  down  a  2  to  the 
left  of  the  1.  The  next  dial  reads  1  and  the  next  9,  so  that 
we  have  a  total  reading  of  9,121  kilowatt-hours.  This  seems 
to  be  plain  enough  to  be  readily  understood  by  almost  any- 
one, but  we  will  consider  one  more  example — No.  2,  Fig. 
312.  Three  of  the  dials  stand  at  0,  the  right  hand  dial  stands 
at  9,  and  since  the  total  value  is  1,000,  we  would  have  900  to 


FOR    MANAGERS    AND    OPERATORS  659 

start  with,  followed  by  000  and  a  1,  or  a  total  of  1,000,900  watt- 
hours. 

Caution. — Before  reading  your  meter  you  must  ascertain 
whether  it  has  a  direct  reading  register  or  one  with  a  multiply- 
ing constant.  Some  meters  are  not  direct  reading,  but  require 
that  the  dial  reading  be  multiplied  by  a  constant  in  order  to 
obtain  the  complete  reading.  This  is  for  the  purpose  of  keeping 
meters  of  various  capacities  of  fairly  uniform  size.  If  the  con- 
stant were  not  used,  meters  of  larger  capacity  would  be  of  greater 
dimensions  than  those  of  smaller  capacity.  If  the  register  face 
bears  the  words  "multiply  by  3"  you  must  multiply  the  actual 
reading  by  3  to  obtain  the  true  value.  If  it  reads  multiply 
by  any  other  number,  then  multiply  the  actual  reading  by 
whatever  the  given  number  may  be. 

The  manager  or  operator  should  always  read  the  meter  when 
the  company's  man  reads  it,  and  make  a  record  of  the  reading 
in  a  book  kept  for  that  purpose.  He  may  then  at  any  time  figure 
his  light  bill  by  the  simple  process  of  reading  the  meter, 
subtracting  from  this  reading  the  last  company  reading,  and 
then  by  multiplying  that  amount  by  his  rate  he  can  tell  pre- 
cisely what  he  owes  at  any  given  time.  Suppose,  for  in- 
stance, when  the  man  reads  the  meter  it  registers  297,480 
watt-hours,  that  being  the  tenth  of  the  month.  On  the  20th 
you  take  another  reading  and  find  that  it  registers  447,580 
watt-hours.  Subtract  one  from  the  other  and  you  find  that 
you  have  consumed  150,100  watt-hours  (we  assume  a  watt- 
hour  register)  or  150.1  kilowatt-hours.  Supposing  your  rate 
to  be  7  cents  per  kilowatt-hour:  150.1  X  7  =  $10.50,  which  will 
be  your  current  consumption  bill  for  that  period. 

Maximum  Demand  Indicators. — Companies  base  their 
charge  to  a  considerable  extent  on  the  amount  of  current 
used,  the  large  consumer  getting  a  lower  rate  than  the  small 
consumer.  This  is  but  right  and  fair,  since  the  proportionate 
overhead  expense  is  much  greater  for  a  small  consumer  than 
for  a  large  one.  However,  in  some  cases  where  the  load  is 
intermittent,  the  price  to  the  consumer  is  based  on  what  is 
known  as  the  "maximum  demand"  rate.  That  is  to  say  if 
the  power  consumption  at  any  time  exceeds  a  certain  fixed 
amount  for  an  appreciable  period  of  time,  there  is  an  addi- 
tional charge  for  the  extra  power.  One  form  of  demand 
instrument  known  as  the  "Wright  Demand  Indicator"  can 
be  used  to  register  or  record  the  highest  amount  of  power 
used  for  a  period  of  five  minutes  or  more  during  any  certain 
period.  For  instance,  where  a  demand  indicator  is  installed, 
assuming  your  normal  current  consumption  to  be  50  amperes, 


660  MOTION   PICTURE   HANDBOOK 

if  you  used  75  amperes  for  a  period  of,  say,  two  or  three 
minutes,  the  instrument  would  take  no  account  of  the  extra 
consumption,  but  if  you  used  that  75  amperes  for  a  period 
of  five  minutes  or  more,  then  the  indicator  would  get  into  action 
and  register  75  amperes,  so  that  when  the  power  company's 
man  came  around  he  would  know  you  had  used  that  amount 
of  current  at  some  time  for  a  period  of  five  minutes  or  more. 

The  Wright  Demand  Indicator  is  installed  near  the  regu- 
lar meter,  and  consists  of  a  U-shaped  tube  containing  sul- 
phuric acid.  When  connected  in  circuit  the  current  which  is 
used  passes  through  a  coil  near  one  leg  of  the  U-shaped 
tube,  the  same  being  in  effect  an  air  chamber  the  bottom  end 
of  which  is  corked  by  the  mercury.  This  coil  is  made  of 
wire  calculated  to  carry  a  certain  definite  number  of  am- 
peres, and  so  long  as  the  current  does  not  exceed  that 
amount,  the  coil  does  not  become  heated  beyond  a  certain 
point,  but  if  there  is  current  consumed  in  excess  the  coil 
heats  in  exact  proportion  to  the  excess  of  current  and  the 
heat  thus  generated  expands  the  air  inside  the  leg  of  the 
U  tube.  This  heating  and  expansion  of  the  air  is  calculated 
to  consume  a  period  of  five  minutes,  and  its  effect  is  to  force 
the  liquid  up  the  other  leg  of  the  tube  and  over  into  an  ex- 
tension chamber,  the  quantity  of  liquid  forced  over  being  in 
exact  proportion  to  the  degree  of  heat  generated  in  the  coil, 
and  therefore  to  the  amperage  used.  Having  once  been 
forced  over,  the  liquid  will  remain  there,  and  thus  the  power 
company  has  an  indisputable  and  permanent  register  of  the 
highest  amperage  you  have  used  for  a  period  of  more  than 
five  minutes.  At  the  end  of  the  month  a  reading  is  taken 
of  the  "demand  indicator,"  and  if  the  column  of  liquid  which 
has  been  forced  into  the  measuring  tube  is  beyond  a  cer- 
tain amount,  the  station  charges  a  certain  extra  amount  for 
extra  load.  After  the  reading  has  been  taken,  the  indicator 
is  unfastened  and  the  tube  tilted  until  the  liquid  runs  back 
out  of  the  measuring  tube  into  the  U  tube,  whereupon  the 
indicator  is  again  ready  to  begin  operations.  The  reason 
for  this  maximum  demand  charge  is  logical  and  simple  when 
it  is  once  understood. 

If  a  customer  ordinarily  uses  5,500  watts,  or  approximately 
7  1/3  h.  p.,  the  power  company  supplying  him  must  provide 
that  amount  of  plant  capacity  for  that  particular  customer. 
Allowing  for  losses  in  generation,  transmission  of  the  cur- 
rent, etc.,  this  means  about  10  h.  p.  in  boilers,  engines,  gener- 
ators, transmission  lines  and  transformers,  in  order  finally  to 
deliver  7  1/3  h.  p.  to  the  customer.  It  costs  real  money 


FOR    MANAGERS   AND    OPERATORS  661 

to  provide  plant  capacity.     The  pro  rata  plant  capacity  re- 
quired in  this  case  would  represent  an  investment  of  $2,000, 
upon  which  interest  is  to  be  paid  and  a  sum  set  aside  each  • 
year  to  cover  the  item  of  depreciation. 

The  demand  system  of  rates  is  used  so  that  power  com- 
panies may  get  from  their  customers  this  interest  and  de- 
preciation first,  and  enough  to  cover  the  operating  expense 
and  profit  afterward.  I  could  go  on  and  give  you  a  lot  of 
figures  along  these  lines,  but  all  I  seek  to  do  is  to  explain  to 
you  the  general  action  of  the  indicator,  and  the  reason  for 
its  installation.  Having  covered  this  point  I  believe  the  pur- 
pose, so  far  as  the  operator  or  manager  be  concerned,  is 
fulfilled.  I  might  as  a  last  thought  add  the  following,  par- 
ticularly in  view  of  the  fact  that  the  motion  picture  theatre 
is  often  a  short  time  load,  which,  from  the  power  company's 
point  of  view,  necessitates  the  paying  of  relatively  high  rates. 
Suppose  one  man  uses  10  amperes  at  110  volts  for  one  hour 
a  day,  or  10X110X1  =  1,100  watt-hours;  another  man  uses 
1  ampere  at  110  volts  for  10  hours,  or  1  X  110 X 10  =1,100 
watt-hours.  Now  these  customers  both  consume  precisely 
the  same  number  of  watt-hours,  but  one  man  uses  his  plant 
capacity  one  hour  out  of  twenty-four,  while  the  other  chap  uses 
his  for  ten  hours,  and  it  naturally  follows  that  the  latter  is  en- 
titled to  a  lower  rate  by  reason  of  the  fact  that  the  company 
is  not  obliged  to  install  added  machinery  capacity,  except 
for  one  ampere,  whereas  in  the  other  case  the  machinery 
capacity  must  provide  for  the  added  10  amperes,  although 
that  added  machinery  will  only  be  in  use  one  hour  out  of 
the  twenty-four,  and  must  lie  idle  the  rest  of  the  time. 

EMPLOYES 

A  theatre  will  reap  vast  advantage  by  the  atmosphere  im- 
parted through  and  by  means  of  neat,  energetic,  intelligent, 
uniformed,  courteous  employes.  On  the  other  hand,  sloven- 
ly, ununiformed,  discourteous  or  careless  employes  will  injure 
the  prestige  and  seriously  decrease  the  revenue  of  any 
theatre. 

There  are  two  moving  picture  theatre  employes  whose 
positions  are  of  paramount  importance,  viz:,  the  manager 
and  the  operator.  The  manager,  of  course,  has  the  employ- 
ment and  supervison  of  all  the  help,  as  well  as  the  decision 
as  to  programs  and  many  other  things  of  vital  importance  to 
the  welfare  of  the  theatre.  I  think  few,  if  any,  will  argue 
that  it  is  good  business  policy  to  employ  an  incompetent, 


662  MOTION    PICTURE    HANDBOOK 

careless  man  as  manager,  merely  because  he  may  be  had 
cheaply. 

The  operator  has  in  his  hands  the  making  or  marring  of 
the  performances,  and  upon  his  skill  and  careful,  painstaking 
attention  to  details  depends,  in  very  large  degree,  the  ex- 
cellence of  the  picture  on  the  screen.  It  therefore  follows 
that,  since  the  revenue  at  the  box  office  is  largely  dependent 
upon  the  result  upon  the  screen,  the  operator  should  not 
only  be  a  man  who  thoroughly  understands  the  technical 
details  of  his  profession,  but  he  must  also  be  possessed  of 
sufficient  energy  to  apply  that  knowledge,  and  place  and 
maintain  on  the  screen  a  perfect  projection,  or  projection 
as  nearly  perfect  as  the  apparatus  at  his  disposal  will  produce. 

It  seems  to  me  that,  as  in  the  case  of  the  manager,  it  is 
foolish  to  argue  for  the  employment  of  a  careless,  or  in- 
competent operator  merely  because  he  is  cheap. 

The  appearance  of  the  theatre  lobby  very  frequently  is  the 
deciding  factor  in  inducing  the  passer-by  to  enter,  or  the  re- 
verse. The  doorman  should  be  a  man,  and  not  a  more  or 
less  irresponsible  boy.  He  should  by  all  means  be  neatly 
uniformed  and  of  prepossessing  appearance.  If  the  pro- 
spective patron  sees  an  ununiformed,  unshaved  doorman, 
perhaps  slumped  down  in  a  chair,  or  leaning  against  a  con- 
venient wall,  he  is  likely  .to  conclude  that  the  performance 
is  apt  to  be  equally  sloppy.  I  know  the  term  "sloppy"  is 
not  elegant,  but  somehow  it  fits  remarkably  well. 

The  ticket  seller  should  be  a  bright  and  attractive  young 
lady,  neatly  dressed  and  wideawake.  Many  a  theatre  loses  pat- 
ronage it  might  otherwise  get  simply  because  of  an  untidy 
looking  ticket  office  presided  over  by  an  unprepossessing, 
gum-chewing  girl.  Particularly  at  the  front  of  the  house 
neatness  in  dress  and  a  wideawake  appearance  counts  for 
much,  and  courtesy  is  above  all  things  highly  important. 

Within  the  ushers  should  be  courteous  and  obliging,  con- 
tinually watching  for  vacant  seats,  and  seeking  at  all  times 
for  opportunity  to  do  the  patron  some  service.  Numberless 
are  the  cases  where  theatres  have  obtained  a  steady  patron 
simply  through  some  little  act  of  courtesy  on  the  part  of 
an  employe,  which  in  itself  amounted  to  but  little,  but  con- 
veyed to  the  recipient  the  idea  that  the  management  was 
looking  after  his  interest  and  comfort.  The  wideawake  usher 
will,  when  the  house  is  well  filled,  keep  in  his  mind  the 
location  of  all  vacant  seats  in  the  section  he  serves,  so  that 
when  a  party  or  a  single  individual  enters,  he  will  know  just 
where  they  can  be  seated  to  best  advantage.  These  things 


FOR    MANAGERS   AND    OPERATORS  663 

count  for  much  in  the  mind  of  the  public.  It  is  not  an  inspiring 
sight  to  see  patrons  parading  up  and  down  the  aisle  looking 
for  seats,  while  the  usher  is  doing  the  same  thing.  Save 
in  exceptional  cases  the  usher  ought  to  know  just  where 
those  seats  are.  If  he  cannot  carry  such  things  in  his  mind, 
and  is  not  sufficiently  energetic  to  watch  closely  and  make 
mental  note  when  patrons  get  up  and  leave,  then  he  is  not 
the  right  man  for  the  job. 

Moving  picture  employes  should  also  have  carefully  im- 
pressed upon  them  the  fact  that  merely  because  a  patron 
wears  a  threadbare  coat,  or  a  cheap  dress,  is  no  reason  that 
he  or  she  is  not  entitled  to  receive  exactly  the  same  degree 
of  courtesy  shown  the  man  or  woman  dressed  in  fine  raiment. 

It  is  the  duty  of  the  manager,  and  a  duty  which  he  will, 
if  he  is  the  right  sort  of  manager,  by  no  means  neglect,  to 
spend  most  of  his  time  around  the  theatre  carefully  watching 
the  performance  of  his  employes,  checking  up  results  on  the 
screen,  and  taking  careful  note  of  comments  of  patrons  con- 
cerning the  show,  particularly  as  they  leave  the  theatre.  In 
time  the  manager  will  come  to  know  many  of  his  patrons, 
and  their  views  and  ideas  will  help  him  greatly  in  improving 
the  program  and  the  various  details  of  the  management  of 
the  house.  A  wise  manager  can  in  course  of  time,  by  stu- 
dious courtesy  on  his  own  part  and  enforcing  the  same 
on  the  part  of  his  employes,  build  up  a  large  personal  fol- 
lowing for  his  theatre,  which  will  be  very  valuable  from  the 
dollars  and  cents  point  of  view.  In  fact  the  management  of 
a  theatre  has  so  many  angles  that  its  careful  consideration 
would  require  almost  if  not  quite  an  entire  book. 

Musicians. — The  "musician"  may  mean  a  single  individual 
presiding  over  a  piano,  or  may  mean  an  orchestra  of  many 
pieces.  It  is  too  large  a  subject  to  be  dealt  with  here,  except 
in  generalities. 

Where  a  single  musician  (piano  player)  is  employed  it  is 
of  the  utmost  importance  that  he  or  she  be  "on  the  job" 
from  the  time  the  picture  starts  until  it  stops.  The  presen- 
tation of  a  subject  may  be  immensely  improved  or  may  be 
very  greatly  injured  by  the  work  of  the  musician.  Whether 
or  not  a  single  musician  should  be  uniformed  is  a  question 
open  to  argument.  I  think,  however,  it  will  depend  con- 
siderably on  circumstances  and  the  sex  of  the  musician.  The 
piano  player  must,  of  course,  have  a  wide  repertoire  of  all 
kinds  of  music  at  instant  command,  and  must  be  able  to 
play  "at  sight"  almost  anything  that  is  written. 

It  is   highly  essential   that   the  piano  player  have   a  large 


664  MOTION    PICTURE    HANDBOOK 

fund  of  good  judgment  and  common  sense,  since  in  the 
smaller  theatres  it  will  be  seldom  possible  to  rehearse  and 
plan  out  the  music  for  the  show,  which  latter  is,  as  a  rule, 
changed  every  day.  Therefore  it  is  necessary  that  the  piano 
player  be  able  instantly  to  select  music  which  will  at  least 
fit  in  fairly  well  with  the  action  of  the  film,  and  this  can 
only  be  done  by  one  possessed  of  not  only  a  large  assort- 
ment of  know-it-by-heart  music  but  also  a  fund  of  good 
judgment. 

Where  an  orchestra  is  used  the  members  should  by  all 
means  be  uniformed.  The  subject  of  orchestras  is,  however, 
such  a  large  one  that  I  think  it  is  not  advisable  to  attempt 
to  deal  with  it. 

Connecting  Up  for  Temporary  Show 

THE  following  instructions  are  by  no  means  designed 
for  regular  road  men.  They  are  presumed  to  know 
their  business.  There  are,  however,  from  time  to 
time  small  exhibitors  who  travel  from  town  to  town  with 
their  own  outfit,  covering  only  small  villages,  and  this  par- 
ticular chapter  is  written  to  point  out  to  them  the  various 
things  they  should  look  out  for  in  connecting  up  to  the  local 
plant.  Also  it  is  quite  true  that  city  operators  who  have  had 
no  road  experience  are  frequently  employed  to  go  out  to 
some  town  and  give  a  show  in  a  church,  theatre,  school  or 
lodge  hall,  and  this  is  not  quite  so  simple  a  proposition  as 
appears  on  the  surface. 

First,  be  very  sure  that  your  outfit  is  "all  there"  before 
starting  out.  Unless  the  exact  throw  and  size  of  picture  is 
known  it  is  always  advisable  to  take  along  at  least  three 
focal  lengths  of  M.  P.  and  stereopticon  lenses,  viz:  a  3^,  4^ 
and  6  inch  M.  P.  lens,  and  a  12,  16  and  21  inch  stereo;  the 
latter  should  always  be  "half  size"  lenses.  It  is  necessary 
that  sufficient  resistance  (rheostats)  be  taken  along  to  handle 
the  voltage  of  the  current,  and,  in  this  connection,  there  is 
a  book  published  by  the  McGraw  Publishing  Company,  239 
West  Thirty-ninth  Street,  New  York  City,  which  gives  the 
voltage,  kind  of  current,  capacity  of  the  generators,  etc.,  of 
every  town  in  the  United  States  and  Canada.  It  is  published 
by  subscription,  and  every  traveling  operator  ought  to  be 
supplied  with  one.  You  should  at  least  take  along  sufficient 
resistance  to  handle  220  volts. 

Before  starting,  examine  the  whole  outfit  and  be  sure  you 
have  not  omitted  some  essential  part.  I  have  known  of 


FOR   MANAGERS   AND    OPERATORS  665 

operators  going  to  some  distant  village  to  give  a  show,  only  to 
discover  upon  arrival  that,  for  instance,  the  machine  crank  had 
been  left  behind,  or  there  were  no  carbons  with  the  outfit, 
or  that  the  lamp  leads  or  lenses  had  been  omitted,  or  there 
was  no  empty  reel  for  the  lower  magazine.  In  this  respect 
an  ounce  of  prevention  is  worth  more  than  a  ton  of  cure, 
and  out  in  an  isolated  village  you  will  not  be  able  to  get  a 
duplicate  of  any  parts  you  may  through  your  carelessness 
have  omitted. 

It  is  advisable  to  take  with  you  at  least  250  feet  of  stranded 
rubber  covered  wire,  size  No.  6  B.  &  S.  On  arriving  at  the 
building  where  the  show  is  to  be  given,  first  ascertain  whether 
the  current  is  A.  C.  or  D.  C.,  and  if  the  former  whether  or 
not  there  is  a  pole  transformer.  If  there  is,  investigate  and 
see  if  it  is  large  enough  to  supply  current  to  the  arc,  in  addi- 
tion to  whatever  else  it  may  be  supplying,  always  remember- 
ing that  a  commercial  transformer  can  carry  a  50  per  cent 
overload  for  an  hour  or  two  without  in  any  way  injuring  it. 
If  you  have  any  doubt  whatever  as  to  the  transformer  being 
large  enough,  it  will  be  advisable  to  see  the  light  plant 
people  about  it,  and  sometimes  a  good  cigar  or  two  will  work 
wonders  in  convincing  the  local  electrican  that  the  trans- 
former is  large  enough  to  carry  your  load.  The  next  thing 
is  to  determine  whether  or  not  the  wires  entering  the  build- 
ing have  sufficient  capacity  to  supply  your  arc  in  addition 
to  whatever  else  they  must  supply.  It  is  also  necessary  to 
investigate  the  size  of  the  meter  (if  there  is  one)  and  fuses. 
If  all.  these  various  things  are  found  to  be  of  ample  size,  the 
next  thing  is  to  determine  the  best  place  to  connect  your 
wires.  If  there  is  a  panel  board  near  where  you  desire  to 
locate  your  machine,  and  it  is  fed  by  wires  large  enough  to 
carry  your  arc,  plus  whatever  else  they  must  carry,  you  may 
connect  to  the  board,  if  possible  through  a  circuit  service 
switch.  However,  this  detail  will  vary  with  different  boards. 
If  there  is  no  panel  board,  or  if  the  panel  board  feeders  are 
too  small,  it  will  probably  be  necessary  to  carry  your  wires 
to  the  main  cutout  and  make  connection  there.  If  the  wires 
entering  the  building  are  too  small  you  will  be  compelled  to 
run  your  own  wires  out  of  some  convenient  window  or  other 
opening,  and  connect  to  the  secondary  (if  there  is  a  trans- 
former) right  up  close  to  the  transformer,  supporting  your 
wires  in  any  convenient  way,  high  enough  so  that  no  one 
can  touch  them.  In  deciding  whether  or  not  the  wires  en- 
tering the  building  are  large  enough  don't  forget  to  figure 
the  load  they  must  carry  in  addition  to  your  arc.  The  volt- 


666  MOTION    PICTURE    HANDBOOK 

age  of  the  current  may  usually  be  ascertained  by  examining 
the  name  plate  on  the  meter  or  pole  transformer,  or  by  using 
your  test  lamp.  If  you  use  a  test  lamp  you  should  have  two 
110  volt  lamps  connected  as  per  Page  257.  You  first  try  wires 
A  and  B.  If  the  lamp  burns  to  candle  power  it  is  approxi- 
mately 220  volts,  and  you  must  have  a  resistance  to  handle 
that  pressure.  If  they  only  burn  to  half  candle  power,  then 
try  wires  A  and  C,  and  if  the  one  lamp  thus  connected  burns 
to  candle  power  the  voltage  is  110.  Having  set  up  your 
machine  and  made  all  electrical  connections,  strike  an  arc 
and  make  sure  that  everything  is  all  right  as  far  as  the  light 
is  concerned.  Try  out  your  mechanism  to  be  sure  nothing  has 
become  disarranged  in  shipment.  Ordinarily  if  the  show  is 
in  a  lodge  hall,  church  or  schoolhouse  you  will  set  your  ma- 
chine on  a  platform  in  the  auditorium,  and  you  should  use  a 
little  common  sense  and  judgment  in  placing  your  rheostats. 
Don't  locate  them  where  somebody  will  stumble  over  them 
or  film  fall  against  them,  or  under  your  machine  where  you 
will  receive  all  the  heat  they  will  generate. 


TESTING   VOLTAGE 

The  traveling  operator  may  ascertain  the  voltage  of  a 
system  in  a  number  of  ways.  A  voltmeter  is  best,  of  course, 
but  such  an  instrument  is  seldom  available.  It  is  exceeding- 
ly unlikely  that  the  voltage  in  any  building  will  exceed  250. 
Connect  two,  ordinary  110  volt  incandescent  lamps  in  series, 
as  per  wires  A-B,  Fig.  107,  Page  257.  Touch  the  end  of  the 
wires  A-B,  Fig.  107,  Page  257,  to  the  circuit  wires,  to  the  live 
binding  post  of  a  switch,  or  to  opposite  fuse  contacts.  If 
the  lamps  burn  above  power  the  voltage  is  above  220,  proba- 
bly 240,  or  250;  if  they  burn  at  candle  power  the  voltage  is 
approximately  220;  if  they  only  glow  red,  try  lamp  wires 
A-C,  Fig.  107,  Page  257.  If  it  burns  to  candle  power  the 
voltage  is  110,  if  above  power  it  is  a  little  above  110,  proba- 
bly 120  or  125;  if  below  candle  power  the  current  is  proba- 
bly 104.  If  it  only  glows  faint  red  the  current  is  probably 
60  or  70.  You  may  also  tell  by  examining  the  plate  on  the 
meter,  if  there  is  one,  or  on  the  motors,  if  there  be  any,  or 
on  the  outside  transformer  if  there  is  any.  The  practical 
man  can  judge  voltage  very  closely  by  the  lamp  test,  and 
even  the  novice  cannot  make  any  serious  error  if  he  follows 
the  above  carefully. 


FOR    MANAGERS    AND    OPERATORS  667 

Is  the  Current  A.  C.  or  D.  C.?— This  point  may  be  deter- 
mined by  (a)  looking  for  a  transformer  outside  the  building 
— if  there  is  one  the  current  is  alternating,  though  its  absence 
does  not  offer  conclusive  proof  that  the  current  is  D.  C; 
(b)  by  looking  at  the  meter  plate,  if  there  is  a  meter,  or  by 
looking  at  the  motor  plates,  if  there  are  any;  (c)  by  slightly 
moistening  the  fingers  and  touching  two  wires  of  opposite 
polarity,  thus  taking  a  slight  shock.  If  it  is  A.  C.  the  current 
will  feel  "jerky."  This  latter  test  is  not  to  be  recommended 
to  the  novice,  or  anyone  else,  for  that  matter,  for  if  you 
should  try  it  and  the  wires  happen  to  be  crossed  with  high 
potential  lines  it  might  prove  to  be  a  very  serious  matter. 

The  best  plan  is  to  call  up  the  powerhouse,  if  it  is  prac- 
tical to  do  so,  and  ask  the  voltage  and  kind  of  current;  also, 
if  alternating,  what  cycle. 

In  this  connection  let  me  add  that  the  traveling  operator 
should  always  consult  the  powerhouse  officials  before  con- 
necting to  lines  in  small  towns,  especially  if  the  show  is  to 
be  given  in  a  church,  hall  or  schoolhouse  supplied  by  a  small 
transformer.  The  transformer  may  be  already  loaded  to 
capacity,  as  may  also  the  street  mains  and  even  the  dynamos. 
If  you  connect  without  permission,  simply  on  the  say-so  of 
some  church  or  school  official  or  citizen  and  damage  is  done 
you  can  be  compelled  to  pay  for  it. 

CHEAP  EQUIPMENT 

As  a  general  proposition  it  may  be  said  that  cheap  equip- 
ment is  very  expensive  equipment  in  the  end.  Except  where 
the  use  is  strictly  temporary  it  seldom  or  never  pays  to  buy 
cheap  projection  apparatus. 

The  wise  manager  will  keep  constantly  before  him  the  fact 
that  his  energies  should  be  directed  first  and  foremost  to  the 
bringing  in  of  every  possible  penny  at  the  box  office,  and 
that  if  a  three  hundred  dollar  projector  will,  by  the  added 
excellence  of  projection,  bring  in  an  added  box  office  revenue 
of  even  so  much  as  three  dollars  per  week,  as  against  a 
projector  costing  two  hundred  dollars,  then  the  high-priced 
machine  is  emphatically  the  best  investment.  He  must  bear 
in  mind  that  if  one  of  the  lenses  is  producing  poor  results, 
those  results  will  operate  to  send  patronage  to  some  rival 
house,  hence  it  should  be  replaced  immediately.  He  should 
not  for  one  instant  forget  that  his  audience  pays  an  admis- 
sion to  his  house  to  see  what  is  spread  forth  upon  his  screen, 
and  that  the  more  excellent  the  performance  the  greater 


668  MOTION    PICTURE   HANDBOOK 

number  of  people  who  will  pay  admission — hence  the  greater 
will  be  the  revenue  of  the  house. 

If  an  experienced  thirty-dollar-a-week  operator,  working 
with  a  three-hundred-dollar  projector,  can  produce  results 
sufficiently  superior  to  those  produced  by  the  fifteen  dollar 
operator  working  with  a  two  hundred  dollar  projector  to 
bring  in  an  added  revenue  of,  say,  even  twenty  dollars  per 
week,  then  the  thirty-dollar  operator  and  the  three-hundred- 
dollar  projector  is  a  good  investment.  And  if  the  average 
increased  revenue  amounts  to  as  much  as  thirty  or  more 
dollars  per  week  (not  at  all  impossible,  or  even  improbable) 
then  the  high-priced  outfit  is  indeed  a  splendid  investment. 

COLORING  INCANDESCENT  LAMPS 

It  is  often  desirable  to  color  incandescent  globes.  Red 
lamps  are  needed  for  exit  lights  and  red,  blue  and  green  are 
used  for  stage  effects.  To  produce  the  desired  colors  dissolve 
one  ounce  of  refined  gelatine  in  one  pint  of  water,  and,  after 
bringing  it  to  a  boil,  add  an  aniline  dye  (Diamond  dyes  are 
excellent  for  the  purpose),  of  the  color  desired,  in  sufficient 
quantity  to  make  the  liquid  very  dense  in  color.  Dip  the 
lamps  in  the  solution  while  it  is  hot,  and  after  removal  let 
them  dry  as  quickly  as  possible.  Repeated  dippings  and  dry- 
ings will  make  the  color  on  the  globe  more  dense.  The 
lamp  may  then  be  dipped  in  a  thin  brass  lacquer,  or,  better 
yet,  in  formaldehyde,  which  will  render  the  color  water- 
proof. Incandescent  globes  may  be  frosted  by  dipping  them 
in  a  strong  solution  or  hydrofluoric  acid. 

A  WARNING 

Those  who  contemplate  the  erection  of  new  theatres  or 
the  remodeling  of  an  old  one  should  be  very  careful  about 
leaving  the  location  and  planning  of  the  operation  room 
entirely  to  the  architect;  also  it  is  not  wise  to  leave  the 
selection  of  a  screen  or  other  projection  equipment  to  his 
judgment. 

Consider  the  question  for  a  moment.  No  matter  how  thor- 
oughly competent  an  architect  may  be  as  to  the  planning  of 
buildings,  by  no  means  does  it  follow  that  he  has  competent 
knowledge  of  the  requirements  of  practical  projection. 

As  a  matter  of  fact  some  of  the  very  best  architects  in  the 
country  have\  perpetrated  the  most  atrocious  blunders  imagi- 
nable in  operating  room  construction  and  location. 

It  is  also,  except  in  isolated  cases,  where  an  operator  of  ex- 


FOR    MANAGERS   AND    OPERATORS  669 

ceptionally  wide  experience  is  found,  not  good  practice  to  place 
operating  room  construction  and  equipment  in  the  hands  of  the 
operator.  He  may  be  a  most  excellent  operator,  but  his  ex- 
perience is  most  likely  limited  to  what  he  has  observed  in  a 
comparatively  small  number  of  theatres. 

There  are  now  available  a  few  really  competent  projection 
engineers,  and  I  would  by  all  means  advise  that  architects'  plans 
be  submitted  to  one  of  these  men  and  that  they  be  requested  to 
suggest  changes,  both  in  the  operating  room  location  and 
its  plans,  which  suggestions  the  architect  shall  be,  if  neces- 
sary, compelled  to  incorporate  into  his  plans.  Remember 
that  the  income  of  your  theatre  will  depend  very  largely 
on  the  result  on  its  screen.  Why  place  that  result  more 
or  less  at  the  mercy  of  an  architect  who,  however  learned 
he  may  be  along  other  lines,  knows  little  or  nothing  about  prac- 
tical projection?  Such  a  course  can  but  result  in  the  hampering 
of  the  work  of  your  operator  and  the  injury  to  greater  or  less 
extent  of  the  picture  on  your  screen. 

It  would  also  be  an  act  of  wisdom  to  consult  a  projection 
engineer  who  has  no  manufacturing  connections  concerning  pro- 
jection apparatus.  You  or  your  operator  may  know  something 
about  a  few  of  the  hundreds  of  different  kinds  of  apparatus, 
but  it  is  the  projection  engineer's  business  to  have  a  com- 
prehensive knowledge  of  them  all. 

A  FEW  DOLLARS  INVESTED  IN  EXPERT  KNOWLEDGE  WILL  SAVE  YOU 
MONEY  IN  THE  END,  AND  AS  A  GENERAL  PROPOSITION  THE  RETURN 
WILL  BE  A  THOUSANDFOLD. 


Airdomes 

During  the  summer  months,  particularly  in  the  south,  air- 
domes  or  open  air  theatres  are  very  popular,  and  they  are 
justly  popular,  too,  because  they  contribute  to  the  the  amuse- 
ment of  the  people  under  the  best  possible  conditions  as  to 
fresh  air,  etc.  In  the  past,  however,  airdome  construc- 
tion has  been  altogether  too  crude.  In  many  of  the  smaller 
towns  it  has  consisted  merely  of  an  open  lot  with  a  high 
fence  around  it,  seats  set  directly  on  the  ground,  a  little 
saw-off  "coop"  containing  one  projector,  and  the  cheapest 
possible  kind  of  screen. 

In  New  York  City  the  law  requires,  among  other  things, 
that  airdomes  must  be  floored,  either  with  wood  or  cement, 
and  that  the  chairs  be  fastened  thereto.  This  is  an  excellent 
rule  to  be  followed.  If  it  pays  to  do  a  thing  at  all  it  pays  to 
do  it  right.  A  dirt  floor  is  by  no  means  satisfactory,  par- 


670  MOTION    PICTURE    HANDBOOK 

ticularly  to  women  wearing  white  skirts  and  good  clothing. 
In  very  small  towns,  however,  the  expense  of  a  cement  or 
lumber  floor  may  be  prohibitive.  In  such  cases  a  floor  of 
tamped  cinders  will  do  fairly  well,  but  the  layer  should  not 
be  less  than  4  inches  thick  after  being  tamped,  and  the 
chairs  must  be  fastened  together  with  wooden  strips  and  the 
sections  thus  formed  fastened  securely  to  stakes  into  the 
ground.  Except  in  very  small  villages,  however,  if  the  air- 
dome  is  designed  to  be  a  permanent  institution  I  would  by 
all  means  advise  the  installation  of  a  proper  floor,  and  that 
means  one  either  of  lumber  or  cement,  preferably  the  latter. 

The  seating  of  an  airdome  should  be  comfortable,  but  of 
such  character  that  it  will  not  be  seriously  affected  by  sun 
or  rain,  since  it  is  exposed  to  the  weather.  What  is  per- 
haps the  most  satisfactory  seating,  everything  considered, 
is  a  regular  theatre  chair,  but  with  unveneered,  heavy,  un- 
painted  but  varnished  wood  backs  and  seats.  Such  seats  may 
be  had.  They  are  substantial,  comfortable,  and  eminently 
suited  to  this  kind  of  installation.  It  is  also  quite  possible 
to  build  a  bench  with  seat  having  the  curves  of  a  regular 
theatre  chair,  the  seat  and  back  to  be  covered  with  three- 
inch  wood  strips  spaced  3%  inches  center  to  center.  The 
seat  should  be  divided  into  19  or  20  inch  spaces.  //  this  be 
carefully  done,  using  the  back  of  a  theatre  chair  to  get  the  angle 
and  slope,  the  result  is  quite  satisfactory.  But  if  a  bench  be 
made  without  attention  to  form  and  without  dividing  it  into 
individual  spaces,  the  result  will  be  very  unsatisfactory.  The 
seat  division  may  consist  of  an  iron  rod  extending  from  a  point 
half  way  between  the  seat  and  the  top  of  the  back  to  the  front 
edge  of  the  seat,  thus  forming  a  combined  division  and  a  very 
substantial  brace.  Use  half-inch  round  iron.  If  smaller,  mis- 
chievous boys  are  apt  to  bend  them,  and  if  the  divisions  be  of 
wood  they  may  be  whittled.  There  are  other  ways  of  doing  it, 
but  the  method  suggested  is  the  best.  All  iron  work  should  be 
coated  with  asphaltum  paint  to  prevent  rusting.  Whatever  the 
character  of  the  seats,  hoivever,  they  must  be  securely  fastened 
to  the  floor.  Loose  seats  are  extremely  dangerous  in  case  of 
panic. 

The  operating  room  should  be  not  less  than  6  feet  wide  by 
8  feet  deep  (front  and  back)  ifit  is  to  contain  one  machine, 
or  8  by  9  if  it  is  to  contain  two.  It  should  be  made  of  con- 
crete or  brick,  have  an  ample  vent  flue,  with  inlet  air  flues 
near  the  floor.  The  ports  of  the  operating  room  should  be 
the  same  .as  for  the  regular  theatre  operating  room 
Page  216). 


FOR    MANAGERS    AND    OPERATORS 


671 


The  screen  should  be  supported  in  such  manner  as  will 
stand  the  strain  of  considerable  air  pressure.  If  it  can  be 
placed  against  a  building,  well  and  good,  otherwise  there 
should  be  timbers  not  less  than  4  by  6  inches,  long  enough  to 
reach  to  the  top  of  the  screen,  and  be  set  into  the  ground  not 
less  than  4  feet.  These  timbers  should  be  guyed  to  the  top  of 
suitable  anchor  posts  set  into  the  ground  not  less  than  3  feet  and 
located  not  less  than  10  feet  back  of  the  screen.  These  guys 
or  braces  should  be  of  2  by  6  lumber.  Remember  with  a  heavy 
wind  blowing  the  screen  will  develop  a  lot  of  pulling  force. 
The  bracing  will,  however,  depend  considerably  upon  the 
location  of  the  screen — that  is  to  say  whether  it  will  receive 


Figure  313. 


the  full  force  of  the  wind  or  not.  If  it  is  protected  by  build- 
ings or  otherwise  the  bracing  and  size  of  uprights  may  be 
modified.  For  the  front  of  the  screen  after  careful  considera- 
tion I  would  recommend  the  following:  that  there  be  a  hood 


672  MOTION    PICTURE    HANDBOOK 

extending  outward  from  the  top  of  the  screen  not  less  than 
8  and  preferably  10  feet,  to  extend  out  at  an  angle  beyond 
the  sides  of  the  screen  to  meet  two  wings  hinged  to  the  edge 
of  the  screen  and  so  arranged  that  they  may  be  closed  when 
the  performance  is  over,  the  idea  being  to  combine  two 
screen-protection  doors  and  an  upper  apron  into  a  hood,  the 
inside  of  which  should  be  painted  dead  black.  The  hood 
above  can  easily  be  supported  by  means  of  wooden  timbers 
extending  out  back  and  anchored  to  the  anchor  posts  hold- 
ing the  top  of  the  screen. 

The  whole  plan  is  shown  in  Figs.  313  and  314,  in  which  we 
are  presumed  to  be  looking  at  the  edge  of  the  screen.  The 
top  of  this  hood  should  be  roofed  with  some  one  of  the 
patent  roofings  so  that  it  will  be  water  tight.  There  is  noth- 
ing at  all  impracticable  in  this  plan,  and  such  a  screen,  by 
thoroughly  shading  from  moonlight,  etc.,  would  add  very 
greatly  to  the  beauty  of  the  picture  in  any  airdome,  and 
would  enable  the  operator  to  show  a  good  picture  on  the 
brightest  moonlight  night,  practically  regardless  of  the 
direction  of  the  moon;  also  it  would  enable  the  use  of  one 
of  the  metallic  surface  screens  without  fear  of  deterioration, 
since  it  would  always  be  protected. 

I  believe  the  two  illustrations  will  enable  you  to  under- 
stand my  idea  in  the  construction  of  the  screen.  Fig.  314  is 
a  front  view  of  the  screen. 

For  an  unprotected  screen  surface  I  would  suggest  wooden 
lath  on  a  substantial  backing,  braced  as  before  suggested, 
and  plastered  with  two  coats  of  very  strong  cement  mortar, 
with  a  finishing  coat  of  cement  mixed  half  cement  and  half 
sand.  This  surface  should  then  be  covered  with  about  three 
coats  of  paint  mixed  as  follows:  White  lead  ground  in  oil 
mixed  with  boiled  linseed  oil  and  a  little  Japan  dryer  for  the 
first  coat.  White  lead  ground  in  oil  mixed  with  one-half 
boiled  linseed  oil  and  one-half  turpentine  for  the  second  coaf. 
White  lead  ground  in  oil  mixed  with  one-third  boiled  linseed 
oil  and  two-thirds  turpentine  for  the  last  coat.  Light  space 
to  be  outlined  in  black  (see  Page  179). 

Selecting  a  Site.— Briefly  the  items  to  be  observed  in  the 
selection  of  a  site  for  airdomes  are  as  follows:  (a)  Does  the 
ground  lie  right?  Is  the  lay  of  the  ground  adapted  to  use  as 
a  theatre  auditorium  floor,  or  will  you  have  to  do  a  lot  of 
grading?  (b)  Will  it  be  necessary  to  erect  a  high  fence  all 
around  the  site,  or  is  a  portion  or  all  of  it  already  taken  care 
of  by  billboards  or  walls  of  other  character?  (c)  Will  the 


FOR   MANAGERS   AND    OPERATORS 


673 


glare  of  the  lights  and  noise  or  the  sound  of  music  call  forth 
protest  from  surrounding  property  owners?  (d)  Does  the  site 
adjoin  a  large  tenement  house,  or  other  buildings  from  which 
a  good  view  of  the  show  may  be  obtained  without  the  for- 


V 


Figure  314. 


mality  of  paying  admission?  (e)  Will  it  be  necessary  to  secure 
signatures  of  adjoining  property  owners  in  order  to  get  a 
license?  If  so,  can  this  be  done?  (f)  What  will  be  the  prob- 
able patronage,  as  judged  by  character  of  surrounding  neigh- 
borhood, and  the  density  of  its  population? 

The  builder  of  an  airdome  should  consider  that  where 
practical  it  is  always  best  to  have  the  screen  face  the  north 
or  east,  since  with  the  screen  facing  either  of  those  directions 
it  is  possible  to  begin  the  show  anywhere  from  twenty 
minutes  to  an  hour  sooner  than  would  be  practical  if  the 
screen  faced  the  south  or  west.  Never  have  your  screen  face 
the  west  if  it  is  possible  to  avoid  it,  unless  the  light  from  the 
west  is  cut  off  by  some  high  building  or  obstruction.  The 
builder  of  an  airdome  will  do  well  to  consider  other  points 


674  MOTION    PICTURE    HANDBOOK 

applying  only  to  certain  localities.  For  instance:  How  about 
mosquitoes?  It  is  rather  a  questionable  proceeding  to  build 
an  airdome  in  a  mosquito  infested  district. 


Projection  by  Limelight 

WHAT  is  known  as  "Limelight"  is  produced  by  direct- 
ing the  flame  of  hydrogen  mixed  with  oxygen  against 
a  pencil  of  unslacked  lime,  or  a  pencil  of  a  substance 
know  as  "Guil  Pastil."  The  flame  in  itself  has  slight  bril- 
liancy, but  is  exceedingly  hot,  and  raises  the  temperature  of  a 
spot  on  the  lime  or  pastil  to  incandescence,  and  it  is  from 
this  spot  all  illumination  emanates. 

While  limelight  is  next  to  electricity  in  brilliance,  still  it 
cannot  be  said  to  approch  the  electric  arc  for  moving  picture 
projection,  although  it  may  be  made  to  serve  very  well  for 
stereopticon  work. 

Those  who  by  force  of  circumstances  are  compelled  to  project 
moving  pictures  with  limelight  will  be  zvell  advised  to  select  films 
of  the  least  possible  density  and  not  attempt  the  projection  of  a 
large  picture.  The  writer  considers  it  unwise  to  attempt  more  than 
a  ten-foot  picture  with  limelight,  and  an  eight  foot  one  is  much 
better.  True,  some  do  project  a  twelve-footer,  but  illumination 
is  not  very  good.  The  amateur  had  better  not  try  more  than 
eight  feet. 

Tank  Gas. — The  best  method  of  producing  limelight  is  by 
purchasing  the  oxygen  and  hydrogen  in  tanks.  Companies 
in  large  cities  make  a  business  of  filling  steel  tanks  with 
these  gases  and  selling  them,  or  rather  the  gas  in  them  to 
exhibitors,  the  price  ranging  from  10  to  15  cents  per  cubic 
foot.  The  oxygen  tanks  are  painted  red  and  the  hydrogen 
tanks  black.  The  tanks  are  usually  loaned  to  the  exhibitor 
free  of  rental,  the  exhibitor  making  a  suitable  cash  deposit  to 
insure  their  return.  Usually  tanks  may  be  had  in  two  sizes, 
viz:,  one  containing  25  and  one  containing  50  cubic  feet.  The 
two  sizes  weigh  about  50  and  100  pounds  respectively.  They  are 
shipped  by  express,  and  if  the  distance  be  long  the  shipping 
charge  may  make  the  gas  very  expensive.  A  pair  of  25-foot 
tanks  should  by  reasonably  economical  management  last  for 
about  three  ordinary  shows  and  the  larger  ones  for  six 
shows.  This  will,  however,  depend  on  the  length  of  show, 
size  of  burner  jet  and  skill  of  the  operator.  Assuming  five 
ordinary  reels  of  film,  many  operators  are  satisfied  to  get 
two  shows  from  the  25-footers  and  four  from  the  fifties. 


FOR  MANAGERS  AND  OPERATORS 


675 


Tank  gas  is,  counting  shipping  charges,  usually  more  ex- 
pensive than  gas  made  with  a  good  portable  outfit,  but  it  is 
superior  in  quality  and  much  more  convenient. 

The  gas  is  under  high  pressure  (250  pounds  per  square  inch; 
some  small  cylinders  are  charged  at  far  greater  pressure) 
and  may  be,  but  should  never  be  used  without  a  "reducing 
valve."  A  reducing  valve  may  be  had  of  any  dealer  in  lime- 
light supplies,  and  should  be  a  part  of  each  limelight  user's 
outfit.  It  is  also  well  to  have  a  pressure  gauge  for  each  tank. 
Some  use  low  pressure  gauges  to  show  pressure  after  gas  has 
passed  the  reducing  valves,  though  this  is,  I  think,  rather 
"fussy"  and  quite  unnecessary.  .  The  tank  gauges  are  not 
absolutely  necessary,  but  are  nevertheless  very  convenient. 

It  is  advisable  to  have  red  hose  for  the  oxygen  connections. 
The  other  may  be  any  color,  but  preferably  black.  This 
is  to  prevent  making  mistakes  in  connection,  which  might 
cause  considerable  annoyance,  or  worse. 


Figure  315. 

In  Fig.  315  we  see  a  typical  burner  for  the  mixing  of  oxy- 
gen and  hydrogen  to  produce  limelight.  The  lime  sets  on 
end  in  the  three  prong  holder  as  shown. 

Gas  Making  Outfits. — There  are  a  number  of  outfits  for 
making  gas  for  limelight  on  the  market.  Among  the  best  of 
these  is  the  Model  B,  made  by  the  Enterprise  Optical  Com- 
pany, Chicago,  full  description  of  which  may  be  had  by 
addressing  the  company. 


676  MOTION    PICTURE   HANDBOOK 

In  this  connection  the  following  letter  taken  from  the 
Projection  Department  of  The  Moving  Picture  World,  July  5, 
1913,  is  of  sufficient  value  to  warrant  receiving  space.  The 
letter  is  from  Mr.  George  A.  Kraus,  Magellan,  New  Mexico. 
Mr.  Kraus  says: 

"My  own  experience  with  gas-making  outfits,  after  having  tried 
every  American  make,  as  well  as  one  outfit  imported  from  England, 
is  that  the  Model  B  Calcium  Gas  Machine,  manufactured  by  the 
Enterprise  Optical  Company,  Chicago,  is  the  lightest  and  most  simple 
in  operation.  It  can  be  set  up  and  charged,  ready  for  use  in  from  five 
to  ten  minutes.  There  is  never  more  than  one  pound  pressure  on  the 
machine.  When  in  use  the  water  in  the  upper  tank  regulates  the  gas. 
So  long  as  one  uses  the  gas  generated,  the  water  in  the  upper  tank 
lowers  to  the  lower  one,  generating  gas  as  needed.  The  moment  you 
shut  off  the  gas  the  machine  stops  generating.  After  the  show,  drain 
off  the  water  and  take  off  the  standpipe.  Should  there  be  any  oxone 
left  over,  it  can  be  used  again  the  next  time  the  machine  Is  charged. 
I  have  run  three  continuous  shows,  of  three  reels  each,  with  one 
charge  of  30  cakes  of  oxone,  but  the  saturator  has  to  be  recharged 
after  every  performance.  I  have  two  saturators  connected  with  the 
standpipe  of  one,  which  gives  sufficient  hydrogen  for  the  three 
shows  without  recharging.  I  project  a  12-foot  picture  at  41  feet,  using 
my  Model  B  gas  machine,  and  get  plenty  of  light.  For  road  work  or 
permanent  location  the  Model  B  could  not  be  too  highly  recommended." 

It  is  not  my  purpose  to  give  directions  for  the  operation 
of  these  outfits,  as  full  and  very  complete  directions  accom- 
pany them  when  purchased.  Suffice  to  say  they  are  all  quite 
practical,  reasonably  simple  in  operation,  and  capable  of  pro- 
ducing a  very  good  light,  at  a  cost  which  is  not  very  much 
different  from  the  cost  of  tank  gas,  when  distances  of  ship- 
ment of  tanks  is  averaged,  always  provided  they  be  handled 
with  intelligence,  be  kept  scrupulously  clean,  and  that  the 
directions  supplied  by  the  manufacturers  be  explicitly  followed. 

Don't  imagine  you  can  produce  good  limelight  by  careless, 
sloppy  methods.  It  simply  can't  be  done.  The  illumination  is 
a  comparatively  weak  one  at  best,  and  good  results  are  hard  to 
get  (for  moving  picture  projection}  under  the  best  conditions. 
This  is  all  the  more  reason  why  the  limelight  user  should  ex- 
ercise every  care  to  get  every  possible  bit  of  light  brilliancy  his 
outfit  is  capable  of  producing. 

The  gasmaking  outfits  make  the  gas  as  it  is  used.  This  is 
accomplished  by  the  use  of  sodium  peroxide,  which,  when 
properly  prepared  and  brought  into  contact  with  water,  gives 
off  approximately  300  times  its  own  bulk  in  oxone.  The 
sodium  peroxide  is  made  into  cakes  and  is  usually  sold  under 
the  trade  name  "Oxone,"  though  some  manufacturers  use 
other  trade  names,  one  of  which  is  "oxylithe."  These  cakes 
are  placed  in  a  reservoir,  which  forms  the  greater  part  of  the 
gas  making  machine,  and  water  is  added,  which  causes  the 


FOR  MANAGERS  AND  OPERATORS 


677 


formation  of  oxygen  the  instant  it  touches  the  "oxone."  The 
water  supply  is  usually  so  arranged  that  the  water,  by  its 
weight,  forms  a  pressure  of  air  in  the  reservoir,  and  this 
pressure  prevents  it  reaching  the  oxone,  which  is  arranged 
somewhat  as  per  Fig.  316.  When  the  gasburner  is  opened 
some  of  the  air  escapes,  which  allows  the  water  to  rise  and 
touch  the  cakes  of  sodium 
peroxide  (oxone),  where- 
upon gas  is  formed,  the 
pressure  increased,  and  the 
water  again  driven  down 
until  enough  gas  is  used 
to  decrease  the  pressure, 
and  again  allow  it  to  rise 
and  touch  the  cakes,  thus 
releasing  a  new  supply  of 
gas,  and  so  on  until  the 
cakes  are  entirely  ex- 
hausted, whereupon  the 
reservoir  must  be  opened, 
cleaned,  and  a  new  supply 
of  cakes  and  water  put  in. 
It  is,  of  course,  very  es- 
sential that  the  reservoir 
be  absolutely  gas  tight. 

W'hen  the  oxygen  has 
been  formed  it  may  be 
combined  with  ether,  or 
with  high  grade  gasoline. 
This  is  accomplished  in  a  Figure  316. 

part  of  the  machine  called 

the  "Saturator."  When  the  oxygen  leaves  the  reservoir  a 
portion  enters  a  tube  and  is  led  directly  to  the  burner.  An- 
other portion  is  led  through  a  tube  to  the  saturator,  in  which 
is  a  pad,  usually  made  of  flannel,  saturated  with  ether,  or 
high  grade  gasoline.  The  oxygen  passes  through  the  satura- 
tor, and  is  there  loaded  with  ether  or  gasoline  (as  the  case 
may  be)  vapor,  which  makes  it  inflammable,  and  enables  it 
to  act  as  a  substitute  for  hydrogen. 

Caution:  In  warm  weather,  and  when  the  saturator  is 
nearly  full,  very  little  oxygen  is  required  to  vaporize  the 
ether,  and  there  is  less  danger  of  explosion  (popping  and 
snapping)  than  when  the  saturator  is  nearly  empty  or  when 
it  is  very  cold. 

The  foregoing  is  merely  intended  to  set  forth  the  principle 


o  o  oooo 
o  o  o  o  o  o 
o  o  o  o  o  oo 

)0  OO  OOO 

bo  ooooo 


678 


MOTION    PICTURE    HANDBOOK 


of  operation  of  these  outfits.  Still  another  plan,  followed  by 
some,  is  to  purchase  oxygen  in  tanks  and  combine  it  with 
ordinary  illuminating  (coal  gas)  gas  from  the  gaslight  sys- 
tem. When  this  is  done,  due  to  the  very  low  pressure  of 
the  illuminating  gas  as  compared  to  that  of  the  oxygen  in 
the  tank,  it  is  advisable,  and  even  necessary  to  have  a  speciil 
form  of  mixing  jet  for  the  lamp.  What  is  known  as  the 
"blow-through"  jet  (to  be  had  of  any  dealer  in  limelight 
supplies)  is  usually  employed  for  this  kind  of  work.  This  jet 
is  illustrated  in  Fig.  317.  The  use  of  the  oxygen-illuminat- 
ing gas  combination  is  not  to  be 
recommended  for  amateurs. 

Limes. — Limes  may  be  had  in 
several  sizes,  up  to  \l/±  inches  in 
diameter.  The  largest  size  is  not 
the  best,  however,  because  it  is 
apt  to  flake  off  or  even  break 
under  the  action  of  heat.  A  one- 
inch  lime  is  preferred  by  most 
operators,  though  some  use  seven- 
eighths  inch. 

Limes  come  in  sealed  cans  or 
jars,  packed  in  powdered  lime. 
They  must  not  be  removed  from 
the  package  until  needed,  and 
the  package  must  be  kept  sealed. 
If  exposed  to  air  containing 
moisture  the  limes  will  slack,  or 
if  there  be  no  moisture  then 

they  will  become  haid  and  unfit  for  use.     Limes  are   quite 
fragile  and  easily  broken. 

Limes  must  be  placed  in  the  burner  so  that  they  will  stand 
perfectly  straight  and  not  wobble  even  the  least  bit  when 
revolved.  If  not  set  true  there  will  be  uneven  illumination 
of  the  screen  as  the  lime  is  revolved  during  the  progress  of 
the  show,  to  expose  a  new  surface  to  the  flame.  The  un- 
evenness  will  be  due  to  varying  distance  of  the  lime  from 
the  tip  of  the  burner. 

Starting  the  Light. — Starting  the  light  is  an  operation 
which,  while  simple,  requires  the  exercise  of  cons'derable 
care.  Having  placed  the  lime  in  position  in  the  lamp,  or 
burner,  as  it  is  usually  called,  and  turned  it  up  so  that  it  does 
not  "wobble"  when  rotated,  pull  the  lime  away  from  the 
burner  tip  from  one-half  to  one  inch,  and,  having  turned  on 


Figure  317. 


FOR    MANAGERS    AND    OPERATORS  679 

the  hydrogen,  light  it  at  the  burner-tip  with  a  match,  just 
as  you  would  light  an  ordinary  gas  jet. 

Caution:  //  using  tank  gas,  remember  it  is  under  heavy 
pressure,  and,  if  there  .is  no  reducing  valve,  open  the  tank 
valve  very  carefully. 

Turn  on  sufficient  hydrogen  to  make  a  flame  two,  three, 
or  four  inches  long  (only  an  experiment  can  determine  the 
proper  length  of  hydrogen  flame,  as  it  will  vary  with  size 
of  tip,  with  different  lots  of  gas  and  with  the  individual  opera- 
tor's ideas)  and,  while  slowly  rotating  the  lime  allow  the 
flame  to  play  on  it  until  well  heated.  This  is  very  necessary, 
particularly  with  a  new  lime  and  with  lime  of  the  larger 
diameters,  since  if  the  full  strength  of  the  oxygen-hydrogen 
flame  be  concentrated  on  a  spot  on  a  cold  lime  the  latter  is 
very  apt  to  crack.  When  the  lime  is  thoroughly  warmed, 
advance  it  to  within  about  one-eighth  inch  of  the  burner  tip, 
and  then,  without  altering  the  hydrogen  flame,  carefully  and 
very  slowly  turn  on  the  oxygen  gas.  The  flame  will  at  once 
diminish  in  size,  and  a  spot  on  the  lime  will  become  incan- 
descent. Keep  turning  on  oxygen  very  slowly,  until  there  is 
a  slight  hissing,  whereupon  ease  off  on  the  oxygen  just  a 
trifle  until  the  hissing  barely  stops.  Some  operators  prefer 
their  light  at  a  point  where  it  does  hiss  just  a  trifle,  but  I 
think  more  light  is  had  just  at  the  point  when  hissing  is 
about  to  begin. 

The  beginner  may  now,  without  any  film  in,  projecting  the 
clear,  white  light  to  the  screen,  turn  just  a  little  more  hydro- 
gen, and  again  bring  the  light  to  the  hissing  point  by  adding 
oxygen.  If  the  screen  brilliance  is  increased,  continue  the 
process  until  there  is  no  further  gain.  If,  on  the  other  hand, 
the  screen  brilliancy  is  less,  then  try  reducing  the  mixture 
by  first  shutting  off  a  little  oxygen,  and  then  a  little  hydrogen. 
Keep  this  up  until  you  find  exactly  what  mixture  gives  the 
greatest  screen  brilliancy,  whereupon  shut  off  the  oxygen  and 
carefully  note  length  of  hydrogen  flame.  Having  done  this 
you  will  be  able  to  tell  pretty  closely  what  length  of  hydro- 
gen flame  will  give  best  results,  which  will  be  a  help  every 
time  you  start  the  light  thereafter. 

Some  operators  turn  on  oxygen  until  a  slight  red  fringe 
appears  at  the  top  of  the  spot  on  the  lime.  I  cannot  recom- 
mend this  method,  however,  as  being  very  accurate. 

When  turning  on  the  oxygen,  if  the  light  should  go  out 
with  a  loud  snap,  or  popping  sound,  quickly  turn  off  the  oxygen, 
relight  the  hydrogen  with  a  match,  and  again  slowly  turn  on 
the  oxygen.  See  "Popping"  or  "Snapping,"  Page  680. 


680  MOTION    PICTURE   HANDBOOK 

Caution:  Remember  when  handling  limelight  gases  that 
oxygen  and  hydrogen  form  an  explosive  mixture  when  com- 
bined. Always  turn  the  hydrogen  on  first  and  off  last.  That 
is  to  say,  when  lighting  up  never  turn  the  oxygen  on  until  the 
hydrogen  has  been  lighted,  and  when  shuting  down  always 
turn  off  the  oxygen  first.  Failure  to  pay  heed  to  this  may  result 
in  damage  to  the  apparatus.  Under  certain  conditions  it 
might  even  cause  a  rather  serious  explosion,  though  that  is 
extremely  unlikely. 

Distance  of  Jet  from  Lime. — The  best  distance  of  tip  of 
burner  jet  from  the  lime  will  vary  slightly  with  size  of  jet 
and  mixture  used.  Test  the  matter  as  follows:  After  the 
light  has  been  burning  long  enough  to  have  its  normal  illu- 
mination, project  the  clear,  white  light  to  the  screen,  and, 
first  making  sure  there  is  no  pit  in  the  lime,  slowly  move  the 
jet  ahead  and  back  until  the  point  of  maximum  illumination 
is  found. 

If  the  tip  be  too  close  to  the  lime  its  point  may  be  melted. 
The  tip  must  be  closer  with  a  soft  lime  than  with  a  hard  one. 

"Popping"  or  "Snapping."— Popping  or  snapping  out  of 
the  light  is  one  of  the  most  annoying  things  the  limelight 
operator  has  to  contend  with.  It  is  seldom  or  never  danger- 
ous, except  to  the  hose  connections. 

When  the  light  snaps  out  turn  off  the  hydrogen  quickly,  else 
the  flame  may  back  up  in  the  tube  and  melt  the  rubber,  or  even 
the  metal  connection  at  the  hydrogen  tank,  the  reducing  valve 
or  the  saturator.  This  only  holds  good  when  using  a  gas  making 
outfit  in  which  oxygen  passes  through  the  saturator. 

Popping  or  snapping  (interchangeable  terms  meaning  the 
same  thing)  is  usually  due  to  excess  of  oxygen  gas.  Remedy: 
Reduce  the  oxygen.  It  may  also  sometimes  be  traced  (though 
seldom)  to  the  tip  being  too  close  to  the  lime.  Popping  is  in 
reality  a  miniature  explosion,  and  sometimes  splits  the  rubber 
tubing  used  for  connections.  For  this  reason 

It  is  best  to  use  flexible,  metal-covered  tubing,  which  may  be 
had  of  any  department  store  or  dealer  in  gas  fixtures.  It  costs 
but  a  few  cents  per  foot.  Paint  the  one  used  for  oxygen  bright 
red,  to  prevent  errors  in  making  connections. 

Light  Goes  Out. — If  your  light  just  simply  "goes  out," 
without  making  any  noise,  it  may  be  due  to  (a)  leaky  or 
"split  tube,  (b)  cracked  or  broken  lime,  (c)  tube  slipped  off 
connection  (should  be  wired  on);  (d)  gas  supply  exhausted; 
(e)  valve  clogged.  The  remedy  for  these  conditions  is  in 
each  case  obvious. 

Revolving  Lime. —  The  action  of  the  flame  on  the  lime  is 


FOR    MANAGERS   AND    OPERATORS  681 

to  form  a  depression  on  its  face,  called  a  "Pit."  As  this  pit 
has  the  effect  of  altering  the  distance  cf  the  lime  from  the 
burner  tip,  it  affects  the  light  brilliancy,  and  it  is  necessary 
occasionally  (time  varies  between  two  and  five  minutes, 
depending  on  hardness  of  lime  and  force  of  gas  jet)  to 
revolve  the  lime  just  enough  to  move  the  pit  out  from  in 
front  of  the  jet  and  present  a  new  surface  to  the  flame.  In 
doing  this  revolve  the  lime  very  slowly,  so  that  the  new  surface 
will  have  time  to  come  up  to  incandescence  as  the  old  one 
cools  off,  else  you  will  produce  a  decidedly  bad  effect  on  the 
screen. 

Hissing  or  Roaring. — Some  operators  supply  their  jet 
enough  oxygen  to  cause  the  light  to  hiss  very  slightly.  Should 
there  be  a  loud  hissing  (some  call  it  "roaring")  it  may  be 
due  to  (a)  Excess  of  oxygen,  in  which  case  the  light  is  apt 
suddenly  to  go  out  with  a  loud  pop,  or  snap.  If  this  occurs 
turn  off  oxygen  quickly  (see  "Popping  or  Snapping")  relight 
the  hydrogen  and  again  turn  .on  the  oxygen,  (b)  Interior 
wall  of  burner  jet  rough.  Remedy:  New  jet.  (c)  Too  much 
gas  for  size  of  jet.  Remedy:  Reduce  gas.  (d)  Wrong  dis- 
tance between  tip  of  burner  and  lime.  Remedy:  Alter  dis- 
tance. A  deep  pit  in  lime  has  this  effect,  and  if  the  lamp 
begins  to  hiss,  without  any  adjustment  having  been  altered, 
the  probable  cause  is  a  deep  pit,  and  revolving  the  lime  will 
remedy  matters. 

Adjusting  the  Lamp. — The  light  must  be  centered  with  the 
condenser,  precisely  as  in  the  case  of  the  electric  arc.  If 
it  be  too  far  away,  too  close,  too  high,  too  low  or  too  far  to 
one  side,  the  screen  illumination  will  be  uneven,  and  there 
will  be  shadows.  By  means  of  the  adjustments  provided, 
move  your  lamp  up,  down  or  sidewise  until  the  screen  L 
evenly  illuminated  all  over,  and  there  is  no  trace  of  shadow. 
The  Condenser. — The  condenser  used  for  limelight  is  the 
same  as  for  the  electric  arc.  It  is  customary  to  carry  the 
spot  a  trifle  larger  than  with  electricity,  due  to  excessive  area 
of  light  source  with  consequent  "fuzzy"  edges  of  spot  at 
cooling  plate  and  use  two  6*/2  lenses,  located  as  close  to  the 
aperture  as  they  can  get  them.  Whether  or  not  this  is  the 
best  practice  I  am  not  prepared  to  say,  but  presume  it  is, 
as  it  is  much  used.  One  operator  even  advises  altering  the 
outfit,  if  necessary,  so  as  to  get  the  lamphouse  cone  right 
up  against  the  machine  aperture,  shoving  it  to  one  side  to 
change  films.  This  does  not  seem  to  the  author  like  good 
practice,  but  try  it  out  anyhow.  I  would  suppose  this  close- 
ness would  require  the  locating  of  the  light  too  far  from  the 


682  MOTION    PICTURE    HANDBOOK 

lens,  which  would  mean  heavy  loss  of  light.  This  is,  how- 
ever, only  my  impression.  I  have  not  actually  tried  it  out. 
I  should  think  a  5l/2  lens  next  the  arc  would  be  better  under 
those  conditions. 

Objective  Lens. — Never  use  an  objective  lens  of  small  diam- 
eter for  limelight  projection.  Be  certain  the  lens  diameter  is 
large  enough  to  receive  the  entire  light  ray  (see  Page  110). 
You  have  a  comparatively  weak  illuminant  at  best,  and  cannot 
afford  to  waste  any  of  it.  Three  and  one-half,  4  and  4^- 
inch  E.  F.  objectives  are.  popular  with  gas  users.  An  eight- 
foot  picture  at  40  feet  seems  to  be  the  one  best  liked.  A  3l/2- 
inch  will  give  close  to  an  eight-foot  picture  at  30  feet,  and  a 
4^-inch  will  give  a  little  more  than  an  eight-foot  picture  at 
40  feet. 

Clean  Lenses. — Clean  lenses  are  extremely  important  when 
using  limelight.  A  dirty  lens  wastes  much  light  by  reflection, 
and  you  cannot  afford  to  waste  any  of  your  light  when  using 
limelight.  See  "Cleaning  Lenses,"  Page  108. 

Fitting  the  Limelight  Burner  into  a  motion  picture  pro- 
jection lamphouse  will  in  the  newer  models  of)  projectors 
call  for  a  new  lamppost,  since,  while  the  lamppost  used  for 
some  of  the  old  style,  small  arc  lamps  will  serve  also  as  a 
support  for  the  limelight  burner,  the  lamppost  of  the  newer, 
heavier  arc  lamps  cannot  be  used  for  the  purpose.  The 
method  of  anchoring  the  new  post  into  place  will  vary  with 
different  makes  of  projector,  and  must  be  left  to  the  ingenuity 
of  the  operator.  Be  sure,  however,  and  get  it  located  so 
that  the  backward  and  forward  adjustment  of  the  arc  lamp 
base  will  still  answer  its  purpose  in  the  forward  and  back 
adjustment  of  the  light  with  relation  to  the  lens. 

Machine  Shutter. — It  is  never  wise  to  use  a  three-wing 
revolving  shutter  with  limelight.  It  cuts  too  much  light, 
and  with  such  a  weak  illuminant  the  flicker  is  not  sufficient 
to  require  the  three  wings.  Use  a  two-winger,  with  the 
blades  reduced  in  width  as  much  as  is  possible  and  avoid  travel 
ghost.  (See  "The  Shutter,"  Page  469.)  It  is  even  claimed 
by  some  operators  that,  when  using  oxygen  and  hydrogen 
with  a  lime  pencil,  they  get  excellent  results  with  a  one- 
wing  shutter.  I  cannot  vouch  for  this.  In  fact  I  am  just  a 
little  bit  skeptical,  but  it  is  nevertheless  worth  trying.  Re- 
move your  regular  shutter  blade  from  its  hub,  cut  a  single 
block  from  stiff  but  thin  cardboard,  using  the  main  shutter 
blade  for  a  pattern,  and  substitute  for  the  regular  shutter 
blade.  If  you  find  it  works  satisfactorily  insert  a  metal  blade 
in  place  of  the  pasteboard.  This  cannot  be  recommended 


FOR    MANAGERS   AND    OPERATORS  683 

where  a  guil  pastil,  ozo-carbi,  or  Bliss  Oxy-Hydro-Cet  Light 
is  used,  as  the  illuminant  is  too  bright.  When  trying  out  the 
one-wing  shutter  idea,  it  will  be  well  to  run  the  machine  a 
little  above  normal  speed.  The  gain  in  light  will  compensate 
for  a  slight  flicker  and  some  injury  to  the  action  in  the  film. 
The  reason  a  one-wing  shutter  may  possibly  be  used  for  lime- 
light projection  is  that  flicker  is  very  much  less  pronounced 
with  a  weak  illuminant  than  with  a  bright  one.  It  is  a  matter 
of  screen  brilliance. 

Screen. — For  limelight  I  would  by  all  means  advise  one  of 
the  best  semi-reflecting  screens  obtainable.  If  a  muslin  or 
plaster  screen  is  used  be  sure  it  is  perfectly  clean  and  white. 
A  Mirror  screen  would  be  ideal,  but  is  too  costly  to  be  conr 
sidered  for  a  gas  installation.  Outline  your  picture  in  black 
(see  Page  178)  and  have  the  room  as  dark  as  you  can  possibly 
get  it.  This  is  especially  important  when  using  a  comparatively 
weak  illuminant. 

Guil  Pastil. — Guil  Pastil  is  the  invention  of  one  M.  Guilbert, 
a  Frenchman.  It  was  first  imported  into  the  United  States, 
in  1913,  by  C.  E.  Lindall,  Bar  Harbor,  Me.  Mr.  Lindall  sub- 
mitted samples  to  the  Projection  Department  of  The  Moving 
Picture  World,  which  had  them  tested  by  practical  gas  men,  who, 
without  exception,  reported  favorably.  The  pastil  is  un- 
questionably a  big  improvement  over  the  lime,  for  which 
it  is  a  substitute.  It  is  made  of  thorium,  ittrium  and  other 
rare  earths,  found  mostly  in  South  America.  Instead  of  set- 
ting upright  in  the  burner  it  is  held  in  horizontal  position, 
the  jet  playing  on  its  end.  It  does  not  need  to  be  revolved, 
as  does  the  lime,  and  once  adjusted  should  not  be  moved. 
Its  density  is  such  that  little  or  no  pit  is  formed  by  the  jet. 
It  comes  in  different  sizes,  but  the  largest,  1/4  by  13/16  inch, 
is  most  popular  with  operators,  and  is  the  size  recommended 
by  the  importer.  The  pastil  is  not  affected  by  dampness, 
but,  owing  to  its  density  and  the  fact  that  is  is  a  very  poor 
conductor  of  heat,  is  very  brittle,  and  must  be  heated  very  slowly, 
else  small  pieces  are  apt  to  snap  off,  thus  injuring  the  pastil. 

The  hydrogen  will  often  blacken  the  pastil  while  heating, 
but  this  does  no  harm,  since  as  soon  as  the  oxygen  is  turned 
on  the  blackness  disappears.  If  preferred  blackening  may 
be  avoided  by  pulling  the  pastil  away  from  the  tip  until  the 
light  has  been  adjusted  to  about  what  experience  tells  the 
operator  it  should  be,  and  then  the  pastil  slowly  advanced 
to  its  normal  position.  Do  the  advancing  very  slowly,  how- 
ever, or  you  may  injure  the  pastil. 


684  MOTION   PICTURE   HANDBOOK 

American-Made  Pastil. — During  the  European  war  it  was 
for  a  time  impossible  to  obtain  French  pastil,  so  Mr.  Lindall 
got  busy  and  produced  an  article  which  some  operators  pro- 
nounce superior,  many  just  as  good,  and  a  few  not  so  good 
as  the  foreign  article.  As  to  quality,  each  man  must  com- 
pare and  judge  for  himself.  Mr.  Lindall  says  the  ingre- 
dients, density,  etc.,  of  the  "home  grown"  article  are  iden- 
tical with  the  French  product.  Personally,  I  believe  the 
Lindall  article  is  practically  as  good  as  the  French. 

The  following  is  reproduced  from  the  Projection  Depart- 
ment of  the  Moving  Picture  World,  June  13,  1914.  It  contains 
valuable  data  for  pastil  users. 

"After  a  three  months'  trial,  under  various  and  severe  tests,  I  have 
finally  discarded  the  old,  faithful  lime  pencil,  for  the  reason  that  since 
using  the  guil  pastil  not  only  are  the  general  results  better,  but  my 
gas  consumption  has  been  reduced  by  fully  one-third.  While  I  formally 
consumed  twelve  cakes  of  oxona,  with  guil  pastil  eight  suffices  for  a 
one  and  a  half-hour  entertainment.  I  now  have  a  pastil  in  my  lamp 
which  has  been  used  for  twelve  consecutive  shows,  and  it  is  still  good 
for  ten  or  twelve  more.  With  careful  handling  the  guil  pastil  should, 
in  my  opinion,  average  at  least  eighteen  entertainments,  each  one  and 
a  half  hours  in  length.  But  great  care  is  necessary  in  handling  the 
pastil,  since  it  is  very  fragile  and  will  not  stand  up  under  rough  treat- 
ment as  will  the  lime  pencil.  The  first  two  pastils  I  tried  lasted  but 
one  show  each.  I  had  been  using  lime  pencils  for  several  years,  and 
one  can  shove  in  a  lime  pencil  at  a  moment's  notice,  turn  on  both 
gases  as  soon  as  it  is  in  place,  and  be  ready  to  begin  the  show.  I  tried 
this  method  with  the  pastil,  with  the  result  that  it  heated  too  quickly 
and  cracked,  and  by  the  time  the  last  reel  was  through  the  pastil  was 
on  the  floor  of  the  lamphouse  in  small  pieces.  I  now  first  turn  a  small 
flame  of  ihydrogen  for  about  three  minutes,  which  heats  the  pastil 
slowly  and  thoroughly;  then  I  turn  on  the  oxygen  gas  slowly,  until 
there  is  a  small  red  ring  on  the  outside  of  the  flame.  This  heats  the 
surface  of  the  pastil  to  white  heat,  delivering  a  steady,  powerful,  white 
light  which  the  line  pencil  can  never  produce.  The  pastil  throws  a 
brilliant,  clear  field  like  an  electric  arc,  except,  of  course,  it  is  not  BO 
powerful  a  light.  To  get  the  best  result  with  the  least  consumption  of 
gas,  ihave  the  burner-tip  at  the  lower  edge  of  the  pastil  and  about  one- 
eighth  of  an  inch  away  from  it.  At  this  distance  the  gas  is  evenly 
distributed  over  the  surface  of  the  pastil,  so  that  its  outer  edge  is  us 
white  as  the  center.  If  the  tip  be  any  closer  than  this  the  light  will 
be  in  the  center  and  the  edges  will  be  darker,  which  makes  for  poor 
results,  besides  pitting  the  pastil  in  the  center,  due  to  the  blast  of  gas 
which  concentrates  on  one  small  spot.  I  get  the  best  results  from  a  nine- 
sixteenths  size  pastil,  using  two  6%  condensers,  projecting  a  12-foot 
picture  at  45  feet." 

Repairing  Guil  Pastil. — Should  a  guil  pastil  by  accident  be 
broken  it  may  be  repaired  and  made  practically  as  good  as 
new  as  follows: 

Take  some  soft  asbestos  wicking,  such  as  is  used  for  pack- 
ing the  stems  of  steam  valves  (to  be  had  at  almost  any  hard- 
ware store)  and  wrap  some  of  it  outside  of  the  pastil,  as 
per  Fig.  318.  Then  over  the  asbestos  wind  some  soft 
wrapping  wire,  such  as  jewelers  use.  Now  make  a  band,  or 


FOR   MANAGERS   AND    OPERATORS 


685 


clamp,  Fig.  318,  out  of  a  heavy  piece  of  sheet  metal  or 
tin.  Bend  this  metal  band  into  shape  so  it  will  act  as  a 
sort  of  shield  and  then  push  it  down  over  the  pastil  and 
holder.  I  would  rec- 

SOf7 Wf 


ommend  that  new  pas- 
tils  be  treated  in  this 
manner.  It  protects  the 
pastil  from  damage  and 
is  worth  while  merely 
as  a  matter  of  protec- 
tion. By  its  use  you 
will  be  enabled  to  turn 
off  the  gas  without  be- 
ing so  careful  about  it. 
The  heat  will  burn  off 
the  wire  as  fast  as  the 
pencil  is  consumed,  so 
that  all  one  needs  to 
do  is  to  smooth  the 
surface  of  the  pencil  oc- 
casionally with  a  piece 
of  No.  00  sandpaper. 

The  S.  A.  Bliss  Oxy- 
Hydro-Cet.—  S.  A.  Bliss, 
Peoria,  111.,  has  perfect- 
ed a  limelight  which 
many  operators  com- 
mend highly.  It  con- 


ffsacsros w/c/,/n/?. 
• 


Figure  318. 


sists  of  commercial  oxygen,  the  same  as  is  ordinarily  used, 
and  a  substitute  for  straight  hydrogen,  consisting  of  hydro- 
gen combined  with  gas  from  calcium  carbide,  and  gasoline 
vapor.  A  specially  constructed  burner  is  supplied  by  the 
Bliss  Company.  By  this  process  it  is  claimed  that  back 
firing,  popping  and  snapping  is  entirely  eliminated.  The 
apparatus  consists  of  a  hydro-cet  generator  and  a  special 
burner.  Oxygen  may  be  generated  from  "oxone"  in  the 
usual  way  or  purchased  in  tanks.  Full  directions  accompany 
the  outfit.  The  light  produced  is  more  brilliant  than  that 
produced  by  the  ordinary  oxygen-hydrogen  gas.  It  may 
be  used  either  with  lime  or  guil  pastil. 

I  am  informed  that  Mr.  Bliss  has  secured  a  special  price 
of  2  cents  per  cubic  foot  on  oxygen  gas  to  be  supplied  to 
his  customers.  This  price  is  made  by  a  large  firm  having 
plants  in  thirty-three  of  the  largest  cities  in  the  United  State.-:. 

Ozo-Carbi.—  This    light    (Patents    393,737    and    724,416)    is 


686  MOTION    PICTURE   HANDBOOK 

made  by  burning  carbide  or  acetylene  gas  with  a  compound 
gas,  which  is  really  a  modified  form  of  oxygen,  called  "Ozo. ' 
Two  tanks  are  used,  one  for  the  carbide  and  one  for  the  ozo 
gas.  Each  gas  is  made  by  the  operator  before  the  enter- 
tainment, .and  is  stored  in  the  tanks.  It  is  then  used  wirh 
the  ordinary  calcium  burner,  just  the  same  as  you  would 
use  the  regular  tank  gas,  and  there  is  no  more  danger  in 
its  use  than  there  is  in  using  oxygen  and  hydrogen  such  as 
is  sold  in  tanks. 

Acetylene  and  oxygen  produce  a  very  high  degree  of  heat 
— in  fact,  the  highest  degree  possible  to  obtain,  othe~  than 
that  of  the  electric  arc.  It  is  not,  however,  practical  to  burn 
them  together  in  a  calcium  jet,  but  acetylene,  or  carbide  gas 
will  burn  together  with  the  Ozo  gas  in  a  calcium  jet,  the  same 
as  oxygen  and  hydrogen  gas,  but  the  result  is  a  higher  degree 
of  heat,  and  hence  a  higher  degree  of  incandescence  of  the  spot 
on  the  lime. 

The  manufacturer  claims  that  the  expense  of  producing 
the  light  is  very  much  less  than  that  of  producing  light  by 
means  of  oxone  combined  with  ether  or  gasoline.  He  also 
claims  a  considerably  higher  illumination. 

For  myself  I  can  vouch  for  the  fact  that  the  ozo-carbi 
forms  an  excellent  illuminant  and  that  it  has  many  apparently 
well  satisfied  users  among  gas  men.  Full  and  complete 
instructions  accompany  each  outfit. 


THE    END 


INDEX  TO  ADVERTISERS 


American  Standard  Motion  Picture  Machine  Company 692 

Bausch  &  Lomb  Optical  Company 690 

Bound  Volumes  of  Moving  Picture  World , 698 

Cine-Mundial 700 

Enterprise  Optical  Manufacturing  Company 691 

Feaster  No-Rewind  Device 694 

Hallberg  Twentieth  Century  A.  C.  to  D.  C.  Motor-Generator.  688 

Hugo  Reisinger 692 

Jones  &  Cammack 694 

Motion  Picture  Electricity 700 

Moving  Picture  World,    Projection    Department 697 

Moving  Picture  World    696 

New  Edison  Super  Kinetoscope 695 

Nicholas  Power  Company 689 

Picture  Theatre  Advertising 699 

Picture  Theatre  Equipment  Company 702 

Precision  Machine  Company,  Inc 693 

Richardson,  F.  H.,  Projection  Engineer 701 

Speer  Carbon  Company 690 

Technique  of  the  Photoplay. 699 


688 


MOTION    PICTURE   HANDBOOK 


THE  OPERATOR  WHO  KNOWS  ASKS  FOR  AND  GETS 

HALLBERG  201^  CENTURY 

A.  C.  TO  D.  C. 

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or  3  phase  A.  C.  Line.      For 
Weight,  450  IBs;  Height,  15";  single  phase,  $40  extra. 

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Other  Sizes  and  Styles 

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J.     O.     n/-\L,L,Oll,r\Xa,  Operators'   Dept. 

36  EAST  23d  St.     •:•     The  House  of  Quality     •:•     NEW  YORK 


FOR   MANAGERS   AND    OPERATORS  689 


gMCM^etK^ffli^ai^gB^^MMasia^^  j 

The  House  of  Power 

Sixteen  Years  of  Knowing  How" 


POWER'S  CAMERAGRAPH  No.  6B 


The  merits  of  the  Power  product,  consistently 
maintained  and  constantly  improved  upon, 
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Write  for  Catalog  R 

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\mi  MIU  mil  \m  mi  niw  HJT  not  \w  m 


690  MOTION    PICTURE    HANDBOOK 


You  cannot  get  good  pictures  with  a  poor  lens  equipment 

Good  pictures  depend  upon  your  lens.  An  operator  who  works 
with  a  poor  lens  cannot  acquire  a  reputation  for  first-class  projection. 
The  owner's  best  investment  is  in 


ausc 

projection  [ens 

They  pay  for  themselves  many  times  over  in  the  increased  patronage 
guaranteed  by  pictures  that  are  brilliant,  clear  and  sharp  to  the 
corners. 

Our  objectives  and  condensers  are  standard,  and  successful  opera- 
tors everywhere  insist  upon  their  use.  The  best  photo-plays  are 
filmed  with  Bausch  &  Lomb  M.  P.  lenses  and  B.  &  L.  projection 
lenses  are  used  in  the  exhibitors'  projection  rooms,  because  they 
are  essential  to  the  best  results. 

The  Edison  and  Nicholas  Power  machines  are  regularly  equipped 
with  Bausch  &  Lomb  objectives.  These  lenses  can  also  be  secured 
through  any  film  exchange. 

Write  to-day  for  our  free  booklet,   "Projection  Lenses."     It  contains 
much   information  of  value  to  both  owner  and   operator 


BAUSCH  &.  LOMB  OPTICAL  CO., 

New  York,  Washington,  Chicago,  San  Francisco 


UP-TO-DATE  MOTION  PICTURE   THEATRES 
USE 

Speer  Projector  Carbons 


Longer   Life— Better  Projection — Brighter  Light 
Look  for  the  Trade- Mark. 

SPEER  CARBON  CO. 

ST.  MARYS,  PA.,  U.  S.  A. 


FOR    MANAGERS    AND    OPERATORS  691 


You  have  promised  your  employer  per- 
fect   projection;    then    insist    on    a    Late    Model 

MOTIOGRAPH. 

Its   Simplicity   and   Durability   ^itk   Perfect  Pro- 
jection v? ill  enable  $ou  to  make  good. 

(See  description  on  Pages  528  to  546) 

The  Enterprise  Optical  Mfg.  Co. 

564  West  Randolph  Street  CHICAGO,  ILL 


692  MOTION    PICTURE    HANDBOOK 


PINK  LABEL  CARBONS 

Are  a  Guarantee  of 

PERFECT  PROJECTION 

FOR  BOTH  A.   C.  &  D.  C. 


On  Every  Package 
SOLE  IMPORTER 

HUGO    REISINGER 

II    BROADWAY          -  -  .          NEW  YORK 


THE  AMERICAN 

STANDARD 
MASTER  MODEL 

THE 
IDEAL  MOTION 

PICTURE 
PROJECTOR 

IDEAL  from  the  oper- 
ator's viewpoint  because 
made  of  comparatively 
fewer,  but  stronger  and 
better  parts,  yet  con- 
taining all  those  me- 
chanical features  and 
exclusive  devices  sup- 
porting the  fundamental 
idea  around  which  the 
Master  Model  is  built: 
that  of  perfection  in 
projection  with  greatest 
ease  of  operation. 
Ideal,  too,  from  the  exhibitor's  viewpoint  because  projection 
troubles  cease  when  American  Standard  Master  Models  are  in  the 
booth.  The  danger  of  breakdowns  and  delays  is  practically 
eliminated;  there  are  no  heavy  repair  bills  to  swell  the  low 
initial  cost  of  the  Master  Model. 

For  complete  particulars  write   to  the  address  below  given. 
AMERICAN     STANDARD     MOTION    PICTURE    MACHINE     CO. 
One   Hundred  Ten  and  Twelve  West  Fortieth   Street.  New  York 


FOR    MANAGERS   AND    OPERATORS 


693 


The  PROJECTOR  that  received  the 
UNANIMOUS  APPROVAL  of  the  U.  S. 
GOVERNMENT  WAR  DEPARTMENT  and 
GRAND  PRIZE  —  PANAMA- PACIFIC 
INTERNATIONAL  EXPOSITION 


THEPRECISION  MACHINE  (O.TNC. 

317  East  34th:  St-  NewYork 


694  MOTION    PICTURE    HANDBOOK 


Made    in   Switzerland. 
Reflex  D.  C.   Carbons  have  a  Specially  Constructed  Negative  with 

Copper   Coated   Core. 

This  letter  was  written  by  an  operator  to  a  friend  who  asked  his 
opinion   of  Reflex   Carbons: 

"I  am  prepared  to  say  that  they  are  a  better  carbon  than  the 
present  carbons  on  the  market. 

"They  make  two  kinds,  one  for  A.  C.  and  one  for  D.  C.  The 
carbons  for  A.  C.  are  by  far  the  best  for  A.  C.  I  ever  used, 
giving  at  least  15%  better  screen  illumination  than  any  other 
brand. 

"The  D.  C.  carbons  have  a  very  brilliant  white  light.  This  is 
caused  by  the  special  pains  they  take  with  their  negative  carbon 
which  has  a  copper  coated  cored  which  gives  a  green  cast  mixed 
with  the  violet  from  the  top  carbon  and  makes  a  Brillianter, 
Whiter  and  Better  light. 

"The  carbons  last  longer  and  give  better  results  than  any  I 
have  used.  They  are  not  a  dirty  carbon  and  don't  fill  your 
lamphouse  full  of  soot. 

"In  fact  they  are  all  that  could  be  desired  in  carbons." 

Write  us  for  descriptive  circular  and  price  liFt.  It  pays  to 
use  the  best. 

JONES  &  CAMMACK,  Sole  Importers 
12  BRIDGE  STREET          ....          NEW  YORK  CITY 


FEASTER 

No-Rewind   Device 

Quickly  Attached   In   Place   of  Upper  Magazine 

SAVES 

TIME-LABOR—BREAKAGE 

WEAR  AND  TEAR  ON  PROJECTOR 

ABSOLUTELY  FIREPROOF 


SEE  IT  AT  YOUR  DEALERS' 


Read  Mr.  Richardson's  Article  On  Page  318 


FEASTER  CORPORATION 

1482  Broadway  New  York 


FOR    MANAGERS    AND    OPERATORS  695 


THE   NEW  EDISON 
SUPER  KINETOSCOPE 

PRICE  $600.00 

^]PHE  most  expensive  projecting  machine 
in  the  world  and  worth  every  dollar  of 
its  cost.  See  this  Handbook  for  descrip- 
tion of  its  mechanical  details  and  write  for 
literature  to 

THOMAS  A.   EDISON,  INC. 

239  LAKESIDE  AVENUE,  ORANGE,  N.  J. 


696  MOTION    PICTURE    HANDBOOK 

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1 


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OLDEST,    LARGEST    AND    BEST 
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Founded  by 

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Yearly 

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tion  Rate 


Domestic  $3.00 
Canada  3.50 
Foreign  4.00 


PROJECTION    DEPARTMENT 

Motion  Picture  Photography 
Educational  Department 

Advertising:  for  Exhibitors 
Foreign  Trade  Notes 

Exhibitors  League  Page 
Music  for  the  Pictures 

Photoplaywright  Section 
Correspondence,  Etc. 
Advertisements  of  Leading 

Film  Manufacturers,  Exchanges  and  Importers 
Machine  Manufacturers  and  Dealers 

Manufacturers  of  Electrical  Equipment 
Theatre  Seating  and  Principal 

Dealers   in   Moving  Picture    Supplies 


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of  great  assistance.  It  is  up-to-date  and  deals 
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•conducted  by  F.  H.  Richardson. 

The  information  in  a  single  issue  may 
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REMEMBER  KNOWLEDGE  BRINGS  SUCCESS 

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Address  all  remittances  for  subscriptions 

Moving  Picture  World 

17  Madison  A\>e.  New  York  City 

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698  MOTION    PICTURE    HANDBOOK 


Bound  Volumes  (Quarterly)  g 

OF  THE 

Moving  Picture  World 

D  g 

Dating  back  to  1912  are  on  sale  by  the 

Chalmers  Publishing  Company.   $1.50 

the  Quarter,  Plus  Express  Charges. 

y  § 

WITHOUT    THEM    THE    THEATRE'S 
EQUIPMENT   IS    INCOMPLETE 

INVALUABLE   TO  MANAGERS  AND  OPERATORS 

O   Within    these    volumes    will    be    found    a    consecutive   C 

D    record  of  the  happenings,  great  and  small,  in  the  motion    D 
O  O 

picture  industry.     With  these  on  your  shelves  you  will 

be  able  quickly  and  accurately  to  resolve  all  doubts — 

to  get  the  facts  as   to   the   date  of   release  of  a  given 

picture;   to  follow  the  rise'  and  development  of  manu- 

6    facturers,   whether   of   films   or   accessories,   and  of  play-   O 

H    ers;   to   answer  questions   of  your  patrons;   in  fine,   to    U 
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have  at  your  elbow  data  the  value  of  which  to  you  at 

times    will    greatly    exceed    the    cost    of    the    volumes. 


The  Chalmers  Publishing  Company 

17   Madison  Avenue,  New  York 


8 


FOR    MANAGERS    AND    OPERATORS  699 


Standard  Publications 


PICTURE  THEATRE  ADVERTISING,  by 
Epes  W.  Sargent,  is  a  work  that  should  be  in  the 
hands  of  every  busy  picture  theatre  manager.  It 
contains  a  fund  of  helpful  information  about 
every  form  of  advertising,  about  type  and  type- 
setting, printing  and  paper.  It  contains  helpful 
information  on  house  programs,  on  framing 
newspaper  advertisements,  on  form  letters, 
posters  or  throwaways.  This  book  is  extremely 
practical  and  contains  more  than  100  examples 
of  plans  that  have  helped  others.  Handsome 
clothboard  binding,  $2  00,  postpaid. 

P.  S. — the  author  conducts  an  exceedingly 
helpful  department  of  two  or  three  pages  on  'this 
important  subject  in  each  weekly  issue  of  the 
MOVING  PICTURE  WORLD. 


TECHNIQUE  OF  THE  PHOTOPLAY,  by 
Epes  W.  Sargent,  is  also  issued  by  the  Chalmers 
Publishing  Company.  It  is  the  most  complete, 
most  instructive  and  most  helpful  work  on  the 
writing  of  photoplay  manuscripts  or  scenarios.  A 
new  third  edition  in  course  of  preparation  when 
this  book  went  to  press.  Address  all  orders  and 
remittances  to 

CHALMERS  PUBLISHING  COMPANY 

MOVING  PICTURE  WORLD 
1  7  Madison  Avenue,  New  York  City 


700  MOTION    PICTURE    HANDBOOK 

STANDARD    PUBLICATIONS 

Motion  Picture  Electricity 
By  J.  H.  Hallberg 

A  275-page  textbook  on  electrical  equip- 
ment, apparatus  and  connections  for 
picture  theatre  houses,  together  with 
data  and  tables  on  current  consumption, 
strength  of  materials  and  practical  sug- 
gestions. Handsome  clothboard  bind- 
ing; $2.50,  postage  prepaid. 

Chalmers  Publishing  Company,  Moving  Picture  World 

17  Madison  Avenue,  New  York  City 


Printed  exclusively  in  the  Spanish  language,  is 
issued  monthly  by  the  Chalmers  Publishing  Com- 
pany. It  is  devoted  exclusively  to  the  moving 
picture  and  outdoor  and  indoor  amusement 
enterprises  in  all  South  American  and  Spanish- 
speaking  countries.  All  correspondence  should  be 
addressed  to 

Cine-Mundial,  Chalmers  Publishing  Company 
17  Madison  Avenue,  New  York  City 


FOR    MANAGERS   AND    OPERATORS  701 

THE  AUTHOR  OF  THIS  BOOK  IS  A 

PROJECTION 
ENGINEER 

For  more  than  eight  years  he  has  studied 
one  thing,  and  one  thing  only,  viz:  Pro- 
jection and  the  things  allied  thereto.  He 
now  offers  his  services  and  advice  as  to 

Operating  Room  Plans 

Operating  Room  Ventilation 
Projection  Machines 

Current  Rectifying  Devices 

Lenses  and  Lens  Systems 
Screens,  Etc.,  Etc. 

If  your  present  results  on  the  screen  are 
unsatisfactory  or  if  your  electric  current 
bills  are  too  high,  he  will  be  pleased  to 
consult  with  you  and  may  be  able  to 
save  you  money  and  improve  results  at 
the  same  time.  Can  personally  visit 
theatres  within  a  radius  of  three  hundred 
miles  of  New  York  City.  Special  ar- 
rangements made  for  longer  distances. 
Fees  reasonable  and  references  cheer- 
fully furnished. 

F.   H.   RICHARDSON 

Room  1434. 
22  East  Seventeenth  Street,  New  York  City 


1 


MOTION    PICTURE    HANDBOOK 


, I 

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I  I 


Projection  Engineers 


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11 


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